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  1. 12 Feb, 2011 7 commits
    • Michel Lespinasse's avatar
      mlock: fix race when munlocking pages in do_wp_page() · e15f8c01
      Michel Lespinasse authored 
      vmscan can lazily find pages that are mapped within VM_LOCKED vmas, and
set the PageMlocked bit on these pages, transfering them onto the
unevictable list.  When do_wp_page() breaks COW within a VM_LOCKED vma,
it may need to clear PageMlocked on the old page and set it on the new
page instead.

This change fixes an issue where do_wp_page() was clearing PageMlocked
on the old page while the pte was still pointing to it (as well as
rmap).  Therefore, we were not protected against vmscan immediately
transfering the old page back onto the unevictable list.  This could
cause pages to get stranded there forever.

I propose to move the corresponding code to the end of do_wp_page(),
after the pte (and rmap) have been pointed to the new page.
Additionally, we can use munlock_vma_page() instead of
clear_page_mlock(), so that the old page stays mlocked if there are
still other VM_LOCKED vmas mapping it.
Signed-off-by: default avatarMichel Lespinasse <walken@google.com>
Reviewed-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: default avatarHugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e15f8c01
    • Yinghai Lu's avatar
      memblock: don't adjust size in memblock_find_base() · e6d2e2b2
      Yinghai Lu authored 
      While applying patch to use memblock to find aperture for 64bit x86.
Ingo found system with 1g + force_iommu

> No AGP bridge found
> Node 0: aperture @ 38000000 size 32 MB
> Aperture pointing to e820 RAM. Ignoring.
> Your BIOS doesn't leave a aperture memory hole
> Please enable the IOMMU option in the BIOS setup
> This costs you 64 MB of RAM
> Cannot allocate aperture memory hole (0,65536K)

the corresponding code:

	addr = memblock_find_in_range(0, 1ULL<<32, aper_size, 512ULL<<20);
	if (addr == MEMBLOCK_ERROR || addr + aper_size > 0xffffffff) {
		printk(KERN_ERR
			"Cannot allocate aperture memory hole (%lx,%uK)\n",
				addr, aper_size>>10);
		return 0;
	}
	memblock_x86_reserve_range(addr, addr + aper_size, "aperture64")

fails because memblock core code align the size with 512M.  That could
make size way too big.

So don't align the size in that case.

actually __memblock_alloc_base, the another caller already align that
before calling that function.

BTW. x86 does not use __memblock_alloc_base...
Signed-off-by: default avatarYinghai Lu <yinghai@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David Miller <davem@davemloft.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Airlie <airlied@linux.ie>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e6d2e2b2
    • Soren Hansen's avatar
      nbd: remove module-level ioctl mutex · de1f016f
      Soren Hansen authored 
      Commit 2a48fc0a ("block: autoconvert trivial BKL users to private
mutex") replaced uses of the BKL in the nbd driver with mutex
operations.  Since then, I've been been seeing these lock ups:

 INFO: task qemu-nbd:16115 blocked for more than 120 seconds.
 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
 qemu-nbd      D 0000000000000001     0 16115  16114 0x00000004
  ffff88007d775d98 0000000000000082 ffff88007d775fd8 ffff88007d774000
  0000000000013a80 ffff8800020347e0 ffff88007d775fd8 0000000000013a80
  ffff880133730000 ffff880002034440 ffffea0004333db8 ffffffffa071c020
 Call Trace:
  [<ffffffff815b9997>] __mutex_lock_slowpath+0xf7/0x180
  [<ffffffff815b93eb>] mutex_lock+0x2b/0x50
  [<ffffffffa071a21c>] nbd_ioctl+0x6c/0x1c0 [nbd]
  [<ffffffff812cb970>] blkdev_ioctl+0x230/0x730
  [<ffffffff811967a1>] block_ioctl+0x41/0x50
  [<ffffffff81175c03>] do_vfs_ioctl+0x93/0x370
  [<ffffffff81175f61>] sys_ioctl+0x81/0xa0
  [<ffffffff8100c0c2>] system_call_fastpath+0x16/0x1b

Instrumenting the nbd module's ioctl handler with some extra logging
clearly shows the NBD_DO_IT ioctl being invoked which is a long-lived
ioctl in the sense that it doesn't return until another ioctl asks the
driver to disconnect.  However, that other ioctl blocks, waiting for the
module-level mutex that replaced the BKL, and then we're stuck.

This patch removes the module-level mutex altogether.  It's clearly
wrong, and as far as I can see, it's entirely unnecessary, since the nbd
driver maintains per-device mutexes, and I don't see anything that would
require a module-level (or kernel-level, for that matter) mutex.
Signed-off-by: default avatarSoren Hansen <soren@linux2go.dk>
Acked-by: default avatarSerge Hallyn <serge.hallyn@canonical.com>
Acked-by: default avatarPaul Clements <paul.clements@steeleye.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@kernel.org>		[2.6.37.x]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      de1f016f
    • Alexander Strakh's avatar
      drivers/rtc/rtc-proc.c: add module_put on error path in rtc_proc_open() · 24a6f5b8
      Alexander Strakh authored 
      In file drivers/rtc/rtc-proc.c seq_open() can return -ENOMEM.

 86        if (!try_module_get(THIS_MODULE))
 87                return -ENODEV;
 88
 89        return single_open(file, rtc_proc_show, rtc);

In this case before exiting (line 89) from rtc_proc_open the
module_put(THIS_MODULE) must be called.

Found by Linux Device Drivers Verification Project
Signed-off-by: default avatarAlexander Strakh <strakh@ispras.ru>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      24a6f5b8
    • Roland Stigge's avatar
      drivers/gpio/pca953x.c: add a mutex to fix race condition · 6e20fb18
      Roland Stigge authored 
      Add a mutex to register communication and handling.  Without the mutex,
GPIOs didn't switch as expected when toggled in a fast sequence of
status changes of multiple outputs.
Signed-off-by: default avatarRoland Stigge <stigge@antcom.de>
Acked-by: default avatarEric Miao <eric.y.miao@gmail.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Marc Zyngier <maz@misterjones.org>
Cc: Ben Gardner <bgardner@wabtec.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      6e20fb18
    • Tejun Heo's avatar
      ptrace: use safer wake up on ptrace_detach() · 01e05e9a
      Tejun Heo authored 
      The wake_up_process() call in ptrace_detach() is spurious and not
interlocked with the tracee state.  IOW, the tracee could be running or
sleeping in any place in the kernel by the time wake_up_process() is
called.  This can lead to the tracee waking up unexpectedly which can be
dangerous.

The wake_up is spurious and should be removed but for now reduce its
toxicity by only waking up if the tracee is in TRACED or STOPPED state.

This bug can possibly be used as an attack vector.  I don't think it
will take too much effort to come up with an attack which triggers oops
somewhere.  Most sleeps are wrapped in condition test loops and should
be safe but we have quite a number of places where sleep and wakeup
conditions are expected to be interlocked.  Although the window of
opportunity is tiny, ptrace can be used by non-privileged users and with
some loading the window can definitely be extended and exploited.
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarRoland McGrath <roland@redhat.com>
Acked-by: default avatarOleg Nesterov <oleg@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      01e05e9a
    • Boaz Harrosh's avatar
      vfs: call rcu_barrier after ->kill_sb() · d863b50a
      Boaz Harrosh authored 
      In commit fa0d7e3d ("fs: icache RCU free inodes"), we use rcu free
inode instead of freeing the inode directly.  It causes a crash when we
rmmod immediately after we umount the volume[1].

So we need to call rcu_barrier after we kill_sb so that the inode is
freed before we do rmmod.  The idea is inspired by Aneesh Kumar.
rcu_barrier will wait for all callbacks to end before preceding.  The
original patch was done by Tao Ma, but synchronize_rcu() is not enough
here.

1. http://marc.info/?l=linux-fsdevel&m=129680863330185&w=2Tested-by: default avatarTao Ma <boyu.mt@taobao.com>
Signed-off-by: default avatarBoaz Harrosh <bharrosh@panasas.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Chris Mason <chris.mason@oracle.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      d863b50a
  3. 11 Feb, 2011 3 commits
    • Linus Torvalds's avatar
      Fix possible filp_cachep memory corruption · 2dab5974
      Linus Torvalds authored 
      In commit 31e6b01f ("fs: rcu-walk for path lookup") we started doing
path lookup using RCU, which then falls back to a careful non-RCU lookup
in case of problems (LOOKUP_REVAL).  So do_filp_open() has this "re-do
the lookup carefully" looping case.

However, that means that we must not release the open-intent file data
if we are going to loop around and use it once more!

Fix this by moving the release of the open-intent data to the function
that allocates it (do_filp_open() itself) rather than the helper
functions that can get called multiple times (finish_open() and
do_last()).  This makes the logic for the lifetime of that field much
more obvious, and avoids the possible double free.
Reported-by: default avatarJ. R. Okajima <hooanon05@yahoo.co.jp>
Acked-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      2dab5974
    • Corey Minyard's avatar
      char/ipmi: fix OOPS caused by pnp_unregister_driver on unregistered driver · d2478521
      Corey Minyard authored 
      This patch fixes an OOPS triggered when calling modprobe ipmi_si a
second time after the first modprobe returned without finding any ipmi
devices.  This can happen if you reload the module after having the
first module load fail.  The driver was not deregistering from PNP in
that case.

Peter Huewe originally reported this patch and supplied a fix, I have a
different patch based on Linus' suggestion that cleans things up a bit
more.

Cc: stable@kernel.org
Cc: openipmi-developer@lists.sourceforge.net
Reviewed-by: default avatarPeter Huewe <peterhuewe@gmx.de>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: default avatarCorey Minyard <cminyard@mvista.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      d2478521
    • Linus Torvalds's avatar
      cap_syslog: accept CAP_SYS_ADMIN for now · ee24aebf
      Linus Torvalds authored 
      In commit ce6ada35 ("security: Define CAP_SYSLOG") Serge Hallyn
introduced CAP_SYSLOG, but broke backwards compatibility by no longer
accepting CAP_SYS_ADMIN as an override (it would cause a warning and
then reject the operation).

Re-instate CAP_SYS_ADMIN - but keeping the warning - as an acceptable
capability until any legacy applications have been updated.  There are
apparently applications out there that drop all capabilities except for
CAP_SYS_ADMIN in order to access the syslog.

(This is a re-implementation of a patch by Serge, cleaning the logic up
and making the code more readable)
Acked-by: default avatarSerge Hallyn <serge@hallyn.com>
Reviewed-by: default avatarJames Morris <jmorris@namei.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      ee24aebf
  5. 10 Feb, 2011 9 commits
  7. 09 Feb, 2011 16 commits
  9. 08 Feb, 2011 5 commits
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