- 12 Apr, 2016 19 commits
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Oliver Neukum authored
commit 5a07975a upstream. The driver can be crashed with devices that expose crafted descriptors with too few endpoints. See: http://seclists.org/bugtraq/2016/Mar/61Signed-off-by:
Oliver Neukum <ONeukum@suse.com> [johan: fix OOB endpoint check and add error messages ] Signed-off-by:
Johan Hovold <johan@kernel.org> Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Oliver Neukum authored
commit 4e9a0b05 upstream. An attack using the lack of sanity checking in probe is known. This patch checks for the existence of a second port. CVE-2016-3136 Signed-off-by:
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Oliver Neukum authored
commit 0b818e39 upstream. Attacks that trick drivers into passing a NULL pointer to usb_driver_claim_interface() using forged descriptors are known. This thwarts them by sanity checking. Signed-off-by:
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Josh Boyer authored
commit 4ec0ef3a upstream. The iowarrior driver expects at least one valid endpoint. If given malicious descriptors that specify 0 for the number of endpoints, it will crash in the probe function. Ensure there is at least one endpoint on the interface before using it. The full report of this issue can be found here: http://seclists.org/bugtraq/2016/Mar/87Reported-by:
Ralf Spenneberg <ralf@spenneberg.net> Signed-off-by:
Josh Boyer <jwboyer@fedoraproject.org> Signed-off-by:
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Oliver Neukum authored
commit 8835ba4a upstream. An attack has become available which pretends to be a quirky device circumventing normal sanity checks and crashes the kernel by an insufficient number of interfaces. This patch adds a check to the code path for quirky devices. Signed-off-by:
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Oliver Neukum authored
commit 0d5ce778 upstream. A typo of j for i led to a logic bug. To rule out future confusion, the variable names are made meaningful. Signed-off-by:
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Oliver Neukum authored
commit 264904cc upstream. Some devices I got show an inability to operate right after power on if they are already connected. They are beyond recovery if the descriptors are requested multiple times. So in case of a timeout we rather bail early and reset again. But it must be done only on the first loop lest we get into a reset/time out spiral that can be overcome with a retry. This patch is a rework of a patch that fell through the cracks. http://www.spinics.net/lists/linux-usb/msg103263.htmlSigned-off-by:
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Maurizio Lombardi authored
commit 84bd6499 upstream. In beiscsi_setup_boot_info(), the boot_kset pointer should be set to NULL in case of failure otherwise an invalid pointer dereference may occur later. Signed-off-by:
Maurizio Lombardi <mlombard@redhat.com> Reviewed-by:
Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by:
Jitendra Bhivare <jitendra.bhivare@broadcom.com> Signed-off-by:
Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by:
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Raghava Aditya Renukunta authored
commit f88fa79a upstream. aac_fib_map_free() calls pci_free_consistent() without checking that dev->hw_fib_va is not NULL and dev->max_fib_size is not zero.If they are indeed NULL/0, this will result in a hang as pci_free_consistent() will attempt to invalidate cache for the entire 64-bit address space (which would take a very long time). Fixed by adding a check to make sure that dev->hw_fib_va and dev->max_fib_size are not NULL and 0 respectively. Fixes: 9ad5204d - "[SCSI]aacraid: incorrect dma mapping mask during blinked recover or user initiated reset" Signed-off-by:
Raghava Aditya Renukunta <raghavaaditya.renukunta@pmcs.com> Reviewed-by:
Tomas Henzl <thenzl@redhat.com> Signed-off-by:
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Douglas Gilbert authored
commit 5ecee0a3 upstream. One of the strange things that the original sg driver did was let the user provide both a data-out buffer (it followed the sg_header+cdb) _and_ specify a reply length greater than zero. What happened was that the user data-out buffer was copied into some kernel buffers and then the mid level was told a read type operation would take place with the data from the device overwriting the same kernel buffers. The user would then read those kernel buffers back into the user space. From what I can tell, the above action was broken by commit fad7f01e ("sg: set dxferp to NULL for READ with the older SG interface") in 2008 and syzkaller found that out recently. Make sure that a user space pointer is passed through when data follows the sg_header structure and command. Fix the abnormal case when a non-zero reply_len is also given. Fixes: fad7f01eSigned-off-by:
Douglas Gilbert <dgilbert@interlog.com> Reviewed-by:
Ewan Milne <emilne@redhat.com> Signed-off-by:
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Andy Lutomirski authored
commit c29016cf upstream. iopl(3) is supposed to work if iopl is already 3, even if unprivileged. This didn't work right on Xen PV. Fix it. Reviewewd-by:
Jan Beulich <JBeulich@suse.com> Signed-off-by:
Andy Lutomirski <luto@kernel.org> Cc: Andrew Cooper <andrew.cooper3@citrix.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jan Beulich <JBeulich@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/8ce12013e6e4c0a44a97e316be4a6faff31bd5ea.1458162709.git.luto@kernel.orgSigned-off-by:
Ingo Molnar <mingo@kernel.org> Signed-off-by:
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Dave Jones authored
commit 7834c103 upstream. Since 4.4, I've been able to trigger this occasionally: =============================== [ INFO: suspicious RCU usage. ] 4.5.0-rc7-think+ #3 Not tainted Cc: Andi Kleen <ak@linux.intel.com> Link: http://lkml.kernel.org/r/20160315012054.GA17765@codemonkey.org.ukSigned-off-by:
Thomas Gleixner <tglx@linutronix.de> Signed-off-by:
Andi Kleen <ak@linux.intel.com> Fixes: 4787c368 "x86/tracing: Add irq_enter/exit() in smp_trace_reschedule_interrupt()" Signed-off-by:
Dave Jones <davej@codemonkey.org.uk> Signed-off-by:
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Bjorn Helgaas authored
commit b84106b4 upstream. The PCI config header (first 64 bytes of each device's config space) is defined by the PCI spec so generic software can identify the device and manage its usage of I/O, memory, and IRQ resources. Some non-spec-compliant devices put registers other than BARs where the BARs should be. When the PCI core sizes these "BARs", the reads and writes it does may have unwanted side effects, and the "BAR" may appear to describe non-sensical address space. Add a flag bit to mark non-compliant devices so we don't touch their BARs. Turn off IO/MEM decoding to prevent the devices from consuming address space, since we can't read the BARs to find out what that address space would be. Signed-off-by:
Bjorn Helgaas <bhelgaas@google.com> Tested-by:
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Dan Carpenter authored
commit 6f3508f6 upstream. dct_sel_base_off is declared as a u64 but we're only using the lower 32 bits because of a shift wrapping bug. This can possibly truncate the upper 16 bits of DctSelBaseOffset[47:26], causing us to misdecode the CS row. Fixes: c8e518d5 ('amd64_edac: Sanitize f10_get_base_addr_offset') Signed-off-by:
Dan Carpenter <dan.carpenter@oracle.com> Cc: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@amd.com> Cc: linux-edac <linux-edac@vger.kernel.org> Link: http://lkml.kernel.org/r/20160120095451.GB19898@mwandaSigned-off-by:
Borislav Petkov <bp@suse.de> Signed-off-by:
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Paolo Bonzini authored
commit 2849eb4f upstream. A guest executing an invalid invept instruction would hang because the instruction pointer was not updated. Fixes: bfd0a56bReviewed-by:
David Matlack <dmatlack@google.com> Signed-off-by:
Paolo Bonzini <pbonzini@redhat.com> Signed-off-by:
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Paolo Bonzini authored
commit e9ad4ec8 upstream. Moving the initialization earlier is needed in 4.6 because kvm_arch_init_vm is now using mmu_lock, causing lockdep to complain: [ 284.440294] INFO: trying to register non-static key. [ 284.445259] the code is fine but needs lockdep annotation. [ 284.450736] turning off the locking correctness validator. ... [ 284.528318] [<ffffffff810aecc3>] lock_acquire+0xd3/0x240 [ 284.533733] [<ffffffffa0305aa0>] ? kvm_page_track_register_notifier+0x20/0x60 [kvm] [ 284.541467] [<ffffffff81715581>] _raw_spin_lock+0x41/0x80 [ 284.546960] [<ffffffffa0305aa0>] ? kvm_page_track_register_notifier+0x20/0x60 [kvm] [ 284.554707] [<ffffffffa0305aa0>] kvm_page_track_register_notifier+0x20/0x60 [kvm] [ 284.562281] [<ffffffffa02ece70>] kvm_mmu_init_vm+0x20/0x30 [kvm] [ 284.568381] [<ffffffffa02dbf7a>] kvm_arch_init_vm+0x1ea/0x200 [kvm] [ 284.574740] [<ffffffffa02bff3f>] kvm_dev_ioctl+0xbf/0x4d0 [kvm] However, it also helps fixing a preexisting problem, which is why this patch is also good for stable kernels: kvm_create_vm was incrementing current->mm->mm_count but not decrementing it at the out_err label (in case kvm_init_mmu_notifier failed). The new initialization order makes it possible to add the required mmdrop without adding a new error label. Reported-by:
Borislav Petkov <bp@alien8.de> Signed-off-by:
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Radim Krčmář authored
commit 7dd0fdff upstream. Discard policy uses ack_notifiers to prevent injection of PIT interrupts before EOI from the last one. This patch changes the policy to always try to deliver the interrupt, which makes a difference when its vector is in ISR. Old implementation would drop the interrupt, but proposed one injects to IRR, like real hardware would. The old policy breaks legacy NMI watchdogs, where PIT is used through virtual wire (LVT0): PIT never sends an interrupt before receiving EOI, thus a guest deadlock with disabled interrupts will stop NMIs. Note that NMI doesn't do EOI, so PIT also had to send a normal interrupt through IOAPIC. (KVM's PIT is deeply rotten and luckily not used much in modern systems.) Even though there is a chance of regressions, I think we can fix the LVT0 NMI bug without introducing a new tick policy. Reported-by:
Yuki Shibuya <shibuya.yk@ncos.nec.co.jp> Reviewed-by:
Radim Krčmář <rkrcmar@redhat.com> Signed-off-by:
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Anton Staaf authored
commit 679315e5 upstream. Add support for Google devices that export simple serial interfaces using the vendor specific SubClass/Protocol pair 0x50/0x01. Signed-off-by:
Anton Staaf <robotboy@chromium.org> Reviewed-by:
Benson Leung <bleung@chromium.org> [johan: move id entries and update Kconfig] Signed-off-by:
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Nicholas Bellinger authored
commit 7f54ab5f upstream. This patch fixes a recent ABORT_TASK regression associated with commit febe562c, where a left-over target_put_sess_cmd() would still be called when __target_check_io_state() detected a command has already been completed, and explicit ABORT must be avoided. Note commit febe562c dropped the local kref_get_unless_zero() check in core_tmr_abort_task(), but did not drop this extra corresponding target_put_sess_cmd() in the failure path. So go ahead and drop this now bogus target_put_sess_cmd(), and avoid this potential use-after-free. Reported-by:
Dan Lane <dracodan@gmail.com> Cc: Quinn Tran <quinn.tran@qlogic.com> Cc: Himanshu Madhani <himanshu.madhani@qlogic.com> Cc: Sagi Grimberg <sagig@mellanox.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Hannes Reinecke <hare@suse.de> Cc: Andy Grover <agrover@redhat.com> Cc: Mike Christie <mchristi@redhat.com> Signed-off-by:
Nicholas Bellinger <nab@linux-iscsi.org> Signed-off-by:
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- 16 Mar, 2016 20 commits
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Greg Kroah-Hartman authored
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Greg Kroah-Hartman authored
This reverts commit 06b41945 which is commit c840ac6a upstream. It's been widely reported that this patch breaks existing userspace applications when backported to the stable kernel releases. As no fix seems to be forthcoming, just revert it to let systems work again. Reported-by:
"J. Paul Reed" <preed@sigkill.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by:
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Rusty Russell authored
commit 8244062e upstream. For CONFIG_KALLSYMS, we keep two symbol tables and two string tables. There's one full copy, marked SHF_ALLOC and laid out at the end of the module's init section. There's also a cut-down version that only contains core symbols and strings, and lives in the module's core section. After module init (and before we free the module memory), we switch the mod->symtab, mod->num_symtab and mod->strtab to point to the core versions. We do this under the module_mutex. However, kallsyms doesn't take the module_mutex: it uses preempt_disable() and rcu tricks to walk through the modules, because it's used in the oops path. It's also used in /proc/kallsyms. There's nothing atomic about the change of these variables, so we can get the old (larger!) num_symtab and the new symtab pointer; in fact this is what I saw when trying to reproduce. By grouping these variables together, we can use a carefully-dereferenced pointer to ensure we always get one or the other (the free of the module init section is already done in an RCU callback, so that's safe). We allocate the init one at the end of the module init section, and keep the core one inside the struct module itself (it could also have been allocated at the end of the module core, but that's probably overkill). [ Rebased for 4.4-stable and older, because the following changes aren't in the older trees: - e0224418: adds arg to is_core_symbol - 7523e4dc: module_init/module_core/init_size/core_size become init_layout.base/core_layout.base/init_layout.size/core_layout.size. Original commit: 8244062e ] Reported-by:
Weilong Chen <chenweilong@huawei.com> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=111541Signed-off-by:
Rusty Russell <rusty@rustcorp.com.au> Signed-off-by:
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Jason Andryuk authored
commit a6807590 upstream. The comparisons should be >= since 0x800 and 0x80 require an additional bit to store. For the 3 byte case, the existing shift would drop off 2 more bits than intended. For the 2 byte case, there should be 5 bits bits in byte 1, and 6 bits in byte 2. Signed-off-by:
Jason Andryuk <jandryuk@gmail.com> Reviewed-by:
Laszlo Ersek <lersek@redhat.com> Cc: Peter Jones <pjones@redhat.com> Cc: Matthew Garrett <mjg59@coreos.com> Cc: "Lee, Chun-Yi" <jlee@suse.com> Signed-off-by:
Matt Fleming <matt@codeblueprint.co.uk> Signed-off-by:
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Matt Fleming authored
commit e246eb56 upstream. Laszlo explains why this is a good idea, 'This is because the pstore filesystem can be backed by UEFI variables, and (for example) a crash might dump the last kilobytes of the dmesg into a number of pstore entries, each entry backed by a separate UEFI variable in the above GUID namespace, and with a variable name according to the above pattern. Please see "drivers/firmware/efi/efi-pstore.c". While this patch series will not prevent the user from deleting those UEFI variables via the pstore filesystem (i.e., deleting a pstore fs entry will continue to delete the backing UEFI variable), I think it would be nice to preserve the possibility for the sysadmin to delete Linux-created UEFI variables that carry portions of the crash log, *without* having to mount the pstore filesystem.' There's also no chance of causing machines to become bricked by deleting these variables, which is the whole purpose of excluding things from the whitelist. Use the LINUX_EFI_CRASH_GUID guid and a wildcard '*' for the match so that we don't have to update the string in the future if new variable name formats are created for crash dump variables. Reported-by:
Peter Jones <pjones@redhat.com> Tested-by:
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Peter Jones authored
commit ed8b0de5 upstream. "rm -rf" is bricking some peoples' laptops because of variables being used to store non-reinitializable firmware driver data that's required to POST the hardware. These are 100% bugs, and they need to be fixed, but in the mean time it shouldn't be easy to *accidentally* brick machines. We have to have delete working, and picking which variables do and don't work for deletion is quite intractable, so instead make everything immutable by default (except for a whitelist), and make tools that aren't quite so broad-spectrum unset the immutable flag. Signed-off-by:
Lee, Chun-Yi <jlee@suse.com> Acked-by:
Matthew Garrett <mjg59@coreos.com> Signed-off-by:
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Peter Jones authored
commit 8282f5d9 upstream. All the variables in this list so far are defined to be in the global namespace in the UEFI spec, so this just further ensures we're validating the variables we think we are. Including the guid for entries will become more important in future patches when we decide whether or not to allow deletion of variables based on presence in this list. Signed-off-by:
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Peter Jones authored
commit 3dcb1f55 upstream. Actually translate from ucs2 to utf8 before doing the test, and then test against our other utf8 data, instead of fudging it. Signed-off-by:
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Peter Jones authored
commit e0d64e6a upstream. Translate EFI's UCS-2 variable names to UTF-8 instead of just assuming all variable names fit in ASCII. Signed-off-by:
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Peter Jones authored
commit 73500267 upstream. This adds ucs2_utf8size(), which tells us how big our ucs2 string is in bytes, and ucs2_as_utf8, which translates from ucs2 to utf8.. Signed-off-by:
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Marcelo Tosatti authored
commit 7cae2bed upstream. As reported at https://bugs.launchpad.net/qemu/+bug/1494350, it is possible to have vcpu->arch.st.last_steal initialized from a thread other than vcpu thread, say the iothread, via KVM_SET_MSRS. Which can cause an overflow later (when subtracting from vcpu threads sched_info.run_delay). To avoid that, move steal time accumulation to vcpu entry time, before copying steal time data to guest. Signed-off-by:
Marcelo Tosatti <mtosatti@redhat.com> Reviewed-by:
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Andreas Schwab authored
commit f15838e9 upstream. Since binutils 2.26 BFD is doing suffix merging on STRTAB sections. But dedotify modifies the symbol names in place, which can also modify unrelated symbols with a name that matches a suffix of a dotted name. To remove the leading dot of a symbol name we can just increment the pointer into the STRTAB section instead. Backport to all stables to avoid breakage when people update their binutils - mpe. Signed-off-by:
Andreas Schwab <schwab@linux-m68k.org> Signed-off-by:
Michael Ellerman <mpe@ellerman.id.au> Signed-off-by:
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Felix Fietkau authored
commit 7a36b930 upstream. The value 5000 was put here with the addition of the timeout field to ieee80211_start_tx_ba_session. It was originally added in mac80211 to save resources for drivers like iwlwifi, which only supports a limited number of concurrent aggregation sessions. Since iwlwifi does not use minstrel_ht and other drivers don't need this, 0 is a better default - especially since there have been recent reports of aggregation setup related issues reproduced with ath9k. This should improve stability without causing any adverse effects. Acked-by:
Avery Pennarun <apenwarr@gmail.com> Signed-off-by:
Felix Fietkau <nbd@openwrt.org> Signed-off-by:
Johannes Berg <johannes.berg@intel.com> Signed-off-by:
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Chris Bainbridge authored
commit f39ea269 upstream. Use kzalloc instead of kmalloc for struct tid_ampdu_rx to initialize the "removed" field (all others are initialized manually). That fixes: UBSAN: Undefined behaviour in net/mac80211/rx.c:932:29 load of value 2 is not a valid value for type '_Bool' CPU: 3 PID: 1134 Comm: kworker/u16:7 Not tainted 4.5.0-rc1+ #265 Workqueue: phy0 rt2x00usb_work_rxdone 0000000000000004 ffff880254a7ba50 ffffffff8181d866 0000000000000007 ffff880254a7ba78 ffff880254a7ba68 ffffffff8188422d ffffffff8379b500 ffff880254a7bab8 ffffffff81884747 0000000000000202 0000000348620032 Call Trace: [<ffffffff8181d866>] dump_stack+0x45/0x5f [<ffffffff8188422d>] ubsan_epilogue+0xd/0x40 [<ffffffff81884747>] __ubsan_handle_load_invalid_value+0x67/0x70 [<ffffffff82227b4d>] ieee80211_sta_reorder_release.isra.16+0x5ed/0x730 [<ffffffff8222ca14>] ieee80211_prepare_and_rx_handle+0xd04/0x1c00 [<ffffffff8222db03>] __ieee80211_rx_handle_packet+0x1f3/0x750 [<ffffffff8222e4a7>] ieee80211_rx_napi+0x447/0x990 While at it, convert to use sizeof(*tid_agg_rx) instead. Fixes: 788211d8 ("mac80211: fix RX A-MPDU session reorder timer deletion") Signed-off-by:
Chris Bainbridge <chris.bainbridge@gmail.com> [reword commit message, use sizeof(*tid_agg_rx)] Signed-off-by:
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Johannes Berg authored
commit 8bf86273 upstream. Beniamino reported that he was getting an RTM_NEWLINK message for a given interface, after the RTM_DELLINK for it. It turns out that the message is a wireless extensions message, which was sent because the interface had been connected and disconnection while it was deleted caused a wext message. For its netlink messages, wext uses RTM_NEWLINK, but the message is without all the regular rtnetlink attributes, so "ip monitor link" prints just rudimentary information: 5: wlan1: <BROADCAST,MULTICAST> mtu 1500 qdisc mq state DOWN group default link/ether 02:00:00:00:01:00 brd ff:ff:ff:ff:ff:ff Deleted 5: wlan1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default link/ether 02:00:00:00:01:00 brd ff:ff:ff:ff:ff:ff 5: wlan1: <BROADCAST,MULTICAST,UP> link/ether (from my hwsim reproduction) This can cause userspace to get confused since it doesn't expect an RTM_NEWLINK message after RTM_DELLINK. The reason for this is that wext schedules a worker to send out the messages, and the scheduling delay can cause the messages to get out to userspace in different order. To fix this, have wext register a netdevice notifier and flush out any pending messages when netdevice state changes. This fixes any ordering whenever the original message wasn't sent by a notifier itself. Reported-by:
Beniamino Galvani <bgalvani@redhat.com> Signed-off-by:
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Takashi Iwai authored
commit d0784829 upstream. "MBC Mode", "VSS Mode", "VSS HPF Mode" and "Enhanced EQ Mode" ctls in wm8958 codec driver are enum, while the current driver accesses wrongly via value.integer.value[]. They have to be via value.enumerated.item[] instead. Signed-off-by:
Takashi Iwai <tiwai@suse.de> Signed-off-by:
Mark Brown <broonie@kernel.org> Signed-off-by:
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Takashi Iwai authored
commit 8019c0b3 upstream. The DRC Mode like "AIF1DRC1 Mode" and EQ Mode like "AIF1.1 EQ Mode" in wm8994 codec driver are enum ctls, while the current driver accesses wrongly via value.integer.value[]. They have to be via value.enumerated.item[] instead. Signed-off-by:
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Steven Rostedt (Red Hat) authored
commit dc17147d upstream. Commit f3775549 ("tracepoints: Do not trace when cpu is offline") added a check to make sure that tracepoints only get called when the cpu is online, as it uses rcu_read_lock_sched() for protection. Commit 3a630178 ("tracing: generate RCU warnings even when tracepoints are disabled") added lockdep checks (including rcu checks) for events that are not enabled to catch possible RCU issues that would only be triggered if a trace event was enabled. Commit f3775549 only stopped the warnings when the trace event was enabled but did not prevent warnings if the trace event was called when disabled. To fix this, the cpu online check is moved to where the condition is added to the trace event. This will place the cpu online check in all places that it may be used now and in the future. Fixes: f3775549 ("tracepoints: Do not trace when cpu is offline") Fixes: 3a630178 ("tracing: generate RCU warnings even when tracepoints are disabled") Reported-by:
Sudeep Holla <sudeep.holla@arm.com> Tested-by:
Steven Rostedt <rostedt@goodmis.org> Signed-off-by:
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Paul Mackerras authored
commit ccec4456 upstream. Thomas Huth discovered that a guest could cause a hard hang of a host CPU by setting the Instruction Authority Mask Register (IAMR) to a suitable value. It turns out that this is because when the code was added to context-switch the new special-purpose registers (SPRs) that were added in POWER8, we forgot to add code to ensure that they were restored to a sane value on guest exit. This adds code to set those registers where a bad value could compromise the execution of the host kernel to a suitable neutral value on guest exit. Fixes: b005255eReported-by:
Thomas Huth <thuth@redhat.com> Reviewed-by:
David Gibson <david@gibson.dropbear.id.au> Signed-off-by:
Paul Mackerras <paulus@samba.org> Signed-off-by:
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Radim Krčmář authored
commit 7099e2e1 upstream. Linux guests on Haswell (and also SandyBridge and Broadwell, at least) would crash if you decided to run a host command that uses PEBS, like perf record -e 'cpu/mem-stores/pp' -a This happens because KVM is using VMX MSR switching to disable PEBS, but SDM [2015-12] 18.4.4.4 Re-configuring PEBS Facilities explains why it isn't safe: When software needs to reconfigure PEBS facilities, it should allow a quiescent period between stopping the prior event counting and setting up a new PEBS event. The quiescent period is to allow any latent residual PEBS records to complete its capture at their previously specified buffer address (provided by IA32_DS_AREA). There might not be a quiescent period after the MSR switch, so a CPU ends up using host's MSR_IA32_DS_AREA to access an area in guest's memory. (Or MSR switching is just buggy on some models.) The guest can learn something about the host this way: If the guest doesn't map address pointed by MSR_IA32_DS_AREA, it results in #PF where we leak host's MSR_IA32_DS_AREA through CR2. After that, a malicious guest can map and configure memory where MSR_IA32_DS_AREA is pointing and can therefore get an output from host's tracing. This is not a critical leak as the host must initiate with PEBS tracing and I have not been able to get a record from more than one instruction before vmentry in vmx_vcpu_run() (that place has most registers already overwritten with guest's). We could disable PEBS just few instructions before vmentry, but disabling it earlier shouldn't affect host tracing too much. We also don't need to switch MSR_IA32_PEBS_ENABLE on VMENTRY, but that optimization isn't worth its code, IMO. (If you are implementing PEBS for guests, be sure to handle the case where both host and guest enable PEBS, because this patch doesn't.) Fixes: 26a4f3c0 ("perf/x86: disable PEBS on a guest entry.") Reported-by:
Jiří Olša <jolsa@redhat.com> Signed-off-by:
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- 09 Mar, 2016 1 commit
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Greg Kroah-Hartman authored
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