From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Greg Thelen <gthelen@google.com>,
Davidlohr Bueso <davidlohr@hp.com>,
Rik van Riel <riel@redhat.com>,
Manfred Spraul <manfred@colorfullife.com>,
Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: [PATCH 3.11 14/36] ipc,shm: fix shm_file deletion races
Date: Tue, 26 Nov 2013 10:12:24 -0800 [thread overview]
Message-ID: <20131126181028.003422276@linuxfoundation.org> (raw)
In-Reply-To: <20131126181025.029404973@linuxfoundation.org>
3.11-stable review patch. If anyone has any objections, please let me know.
------------------
From: Greg Thelen <gthelen@google.com>
commit a399b29dfbaaaf91162b2dc5a5875dd51bbfa2a1 upstream.
When IPC_RMID races with other shm operations there's potential for
use-after-free of the shm object's associated file (shm_file).
Here's the race before this patch:
TASK 1 TASK 2
------ ------
shm_rmid()
ipc_lock_object()
shmctl()
shp = shm_obtain_object_check()
shm_destroy()
shum_unlock()
fput(shp->shm_file)
ipc_lock_object()
shmem_lock(shp->shm_file)
<OOPS>
The oops is caused because shm_destroy() calls fput() after dropping the
ipc_lock. fput() clears the file's f_inode, f_path.dentry, and
f_path.mnt, which causes various NULL pointer references in task 2. I
reliably see the oops in task 2 if with shmlock, shmu
This patch fixes the races by:
1) set shm_file=NULL in shm_destroy() while holding ipc_object_lock().
2) modify at risk operations to check shm_file while holding
ipc_object_lock().
Example workloads, which each trigger oops...
Workload 1:
while true; do
id=$(shmget 1 4096)
shm_rmid $id &
shmlock $id &
wait
done
The oops stack shows accessing NULL f_inode due to racing fput:
_raw_spin_lock
shmem_lock
SyS_shmctl
Workload 2:
while true; do
id=$(shmget 1 4096)
shmat $id 4096 &
shm_rmid $id &
wait
done
The oops stack is similar to workload 1 due to NULL f_inode:
touch_atime
shmem_mmap
shm_mmap
mmap_region
do_mmap_pgoff
do_shmat
SyS_shmat
Workload 3:
while true; do
id=$(shmget 1 4096)
shmlock $id
shm_rmid $id &
shmunlock $id &
wait
done
The oops stack shows second fput tripping on an NULL f_inode. The
first fput() completed via from shm_destroy(), but a racing thread did
a get_file() and queued this fput():
locks_remove_flock
__fput
____fput
task_work_run
do_notify_resume
int_signal
Fixes: c2c737a0461e ("ipc,shm: shorten critical region for shmat")
Fixes: 2caacaa82a51 ("ipc,shm: shorten critical region for shmctl")
Signed-off-by: Greg Thelen <gthelen@google.com>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
ipc/shm.c | 28 +++++++++++++++++++++++-----
1 file changed, 23 insertions(+), 5 deletions(-)
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -208,15 +208,18 @@ static void shm_open(struct vm_area_stru
*/
static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
{
+ struct file *shm_file;
+
+ shm_file = shp->shm_file;
+ shp->shm_file = NULL;
ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
shm_rmid(ns, shp);
shm_unlock(shp);
- if (!is_file_hugepages(shp->shm_file))
- shmem_lock(shp->shm_file, 0, shp->mlock_user);
+ if (!is_file_hugepages(shm_file))
+ shmem_lock(shm_file, 0, shp->mlock_user);
else if (shp->mlock_user)
- user_shm_unlock(file_inode(shp->shm_file)->i_size,
- shp->mlock_user);
- fput (shp->shm_file);
+ user_shm_unlock(file_inode(shm_file)->i_size, shp->mlock_user);
+ fput(shm_file);
ipc_rcu_putref(shp, shm_rcu_free);
}
@@ -986,6 +989,13 @@ SYSCALL_DEFINE3(shmctl, int, shmid, int,
}
shm_file = shp->shm_file;
+
+ /* check if shm_destroy() is tearing down shp */
+ if (shm_file == NULL) {
+ err = -EIDRM;
+ goto out_unlock0;
+ }
+
if (is_file_hugepages(shm_file))
goto out_unlock0;
@@ -1104,6 +1114,14 @@ long do_shmat(int shmid, char __user *sh
goto out_unlock;
ipc_lock_object(&shp->shm_perm);
+
+ /* check if shm_destroy() is tearing down shp */
+ if (shp->shm_file == NULL) {
+ ipc_unlock_object(&shp->shm_perm);
+ err = -EIDRM;
+ goto out_unlock;
+ }
+
path = shp->shm_file->f_path;
path_get(&path);
shp->shm_nattch++;
next prev parent reply other threads:[~2013-11-26 18:20 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-26 18:12 [PATCH 3.11 00/36] 3.11.10-stable review Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 01/36] ACPICA: DeRefOf operator: Update to fully resolve FieldUnit and BufferField refs Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 02/36] libertas: potential oops in debugfs Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 03/36] aacraid: prevent invalid pointer dereference Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 04/36] ACPICA: Return error if DerefOf resolves to a null package element Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 05/36] ACPICA: Fix for a Store->ArgX when ArgX contains a reference to a field Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 06/36] USB: mos7840: fix tiocmget error handling Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 07/36] can: kvaser_usb: fix usb endpoints detection Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 08/36] Btrfs: relocate csums properly with prealloc extents Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 09/36] crypto: ansi_cprng - Fix off by one error in non-block size request Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 10/36] crypto: s390 - Fix aes-cbc IV corruption Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 11/36] can: c_can: Fix RX message handling, handle lost message before EOB Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 12/36] alx: Reset phy speed after resume Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 13/36] ipc,shm: correct error return value in shmctl (SHM_UNLOCK) Greg Kroah-Hartman
2013-11-26 18:12 ` Greg Kroah-Hartman [this message]
2013-11-26 18:12 ` [PATCH 3.11 15/36] drm/nvc0-/gr: fix a number of missing explicit array terminators Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 16/36] thinkpad_acpi: Fix build error when CONFIG_SND_MAX_CARDS > 32 Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 17/36] SUNRPC: dont map EKEYEXPIRED to EACCES in call_refreshresult Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 18/36] sched, idle: Fix the idle polling state logic Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 19/36] PCI: Allow PCIe Capability link-related register access for switches Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 20/36] PCI: Remove PCIe Capability version checks Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 21/36] PCI: Support PCIe Capability Slot registers only for ports with slots Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 22/36] perf/ftrace: Fix paranoid level for enabling function tracer Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 23/36] ACPI / EC: Ensure lock is acquired before accessing ec struct members Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 24/36] ACPI / video: Quirk initial backlight level 0 Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 25/36] ACPI / hotplug: Fix handle_root_bridge_removal() Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 26/36] ACPI / hotplug: Do not execute "insert in progress" _OST Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 27/36] Staging: zram: Fix access of NULL pointer Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 28/36] staging: comedi: avoid memleak for subdevice private Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 29/36] Drivers: hv: vmbus: Fix a bug in channel rescind code Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 30/36] rt2x00: fix a crash bug in the HT descriptor handling fix Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 31/36] rt2x00: check if device is still available on rt2x00mac_flush() Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 32/36] rt2x00: rt2800lib: fix VGC adjustment for RT5592 Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 33/36] rt2x00: fix HT TX descriptor settings regression Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 34/36] Bluetooth: revert: "Bluetooth: Add missing reset_resume dev_pm_ops" Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 35/36] Revert "ima: policy for RAMFS" Greg Kroah-Hartman
2013-11-26 18:12 ` [PATCH 3.11 36/36] exec/ptrace: fix get_dumpable() incorrect tests Greg Kroah-Hartman
2013-11-27 4:12 ` [PATCH 3.11 00/36] 3.11.10-stable review Guenter Roeck
2013-11-27 22:30 ` Shuah Khan
2013-11-28 10:56 ` Satoru Takeuchi
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