The function dup_task() may fail at the following function calls in the
following order.
0) alloc_task_struct_node()
1) alloc_thread_info_node()
2) arch_dup_task_struct()
Error by 0) is not a matter, it can just return. But error by 1) requires
releasing task_struct allocated by 0) before it returns. Likewise, error
by 2) requires releasing task_struct and thread_info allocated by 0) and
1).
The existing error handling calls free_task_struct() and
free_thread_info() which do not only release task_struct and thread_info,
but also call architecture specific arch_release_task_struct() and
arch_release_thread_info().
The problem is that task_struct and thread_info are not fully initialized
yet at this point, but arch_release_task_struct() and
arch_release_thread_info() are called with them.
For example, x86 defines its own arch_release_task_struct() that releases
a task_xstate. If alloc_thread_info_node() fails in dup_task(),
arch_release_task_struct() is called with task_struct which is just
allocated and filled with garbage in this error handling.
This actually happened with tools/testing/fault-injection/failcmd.sh
# env FAILCMD_TYPE=fail_page_alloc \
./tools/testing/fault-injection/failcmd.sh --times=100 \
--min-order=0 --ignore-gfp-wait=0 \
-- make -C tools/testing/selftests/ run_tests
In order to fix this issue, make free_{task_struct,thread_info}() not to
call arch_release_{task_struct,thread_info}() and call
arch_release_{task_struct,thread_info}() implicitly where needed.
Default arch_release_task_struct() and arch_release_thread_info() are
defined as empty by default. So this change only affects the
architectures which implement their own arch_release_task_struct() or
arch_release_thread_info() as listed below.
arch_release_task_struct(): x86, sh
arch_release_thread_info(): mn10300, tile
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Koichi Yasutake <yasutake.koichi@jp.panasonic.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Salman Qazi <sqazi@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The current code can be replaced by vma_pages(). So use it to simplify
the code.
[akpm@linux-foundation.org: initialise `len' at its definition site]
Signed-off-by: Huang Shijie <shijie8@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__mem_open() which is called by both /proc/<pid>/environ and
/proc/<pid>/mem ->open() handlers will allow the use of negative offsets.
/proc/<pid>/mem has negative offsets but not /proc/<pid>/environ.
Clean this by moving the 'force FMODE_UNSIGNED_OFFSET flag' to mem_open()
to allow negative offsets only on /proc/<pid>/mem.
Signed-off-by: Djalal Harouni <tixxdz@opendz.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Brad Spengler <spender@grsecurity.net>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently the following offset and environment address range check in
environ_read() of /proc/<pid>/environ is buggy:
int this_len = mm->env_end - (mm->env_start + src);
if (this_len <= 0)
break;
Large or negative offsets on /proc/<pid>/environ converted to 'unsigned
long' may pass this check since '(mm->env_start + src)' can overflow and
'this_len' will be positive.
This can turn /proc/<pid>/environ to act like /proc/<pid>/mem since
(mm->env_start + src) will point and read from another VMA.
There are two fixes here plus some code cleaning:
1) Fix the overflow by checking if the offset that was converted to
unsigned long will always point to the [mm->env_start, mm->env_end]
address range.
2) Remove the truncation that was made to the result of the check,
storing the result in 'int this_len' will alter its value and we can
not depend on it.
For kernels that have commit b409e578d ("proc: clean up
/proc/<pid>/environ handling") which adds the appropriate ptrace check and
saves the 'mm' at ->open() time, this is not a security issue.
This patch is taken from the grsecurity patch since it was just made
available.
Signed-off-by: Djalal Harouni <tixxdz@opendz.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Brad Spengler <spender@grsecurity.net>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The system deadlocks (at least since 2.6.10) when
call_usermodehelper(UMH_WAIT_EXEC) request triggers
call_usermodehelper(UMH_WAIT_PROC) request.
This is because "khelper thread is waiting for the worker thread at
wait_for_completion() in do_fork() since the worker thread was created
with CLONE_VFORK flag" and "the worker thread cannot call complete()
because do_execve() is blocked at UMH_WAIT_PROC request" and "the khelper
thread cannot start processing UMH_WAIT_PROC request because the khelper
thread is waiting for the worker thread at wait_for_completion() in
do_fork()".
The easiest example to observe this deadlock is to use a corrupted
/sbin/hotplug binary (like shown below).
# : > /tmp/dummy
# chmod 755 /tmp/dummy
# echo /tmp/dummy > /proc/sys/kernel/hotplug
# modprobe whatever
call_usermodehelper("/tmp/dummy", UMH_WAIT_EXEC) is called from
kobject_uevent_env() in lib/kobject_uevent.c upon loading/unloading a
module. do_execve("/tmp/dummy") triggers a call to
request_module("binfmt-0000") from search_binary_handler() which in turn
calls call_usermodehelper(UMH_WAIT_PROC).
In order to avoid deadlock, as a for-now and easy-to-backport solution, do
not try to call wait_for_completion() in call_usermodehelper_exec() if the
worker thread was created by khelper thread with CLONE_VFORK flag. Future
and fundamental solution might be replacing singleton khelper thread with
some workqueue so that recursive calls up to max_active dependency loop
can be handled without deadlock.
[akpm@linux-foundation.org: add comment to kmod_thread_locker]
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
An fs-thaw ioctl causes deadlock with a chcp or mkcp -s command:
chcp D ffff88013870f3d0 0 1325 1324 0x00000004
...
Call Trace:
nilfs_transaction_begin+0x11c/0x1a0 [nilfs2]
wake_up_bit+0x20/0x20
copy_from_user+0x18/0x30 [nilfs2]
nilfs_ioctl_change_cpmode+0x7d/0xcf [nilfs2]
nilfs_ioctl+0x252/0x61a [nilfs2]
do_page_fault+0x311/0x34c
get_unmapped_area+0x132/0x14e
do_vfs_ioctl+0x44b/0x490
__set_task_blocked+0x5a/0x61
vm_mmap_pgoff+0x76/0x87
__set_current_blocked+0x30/0x4a
sys_ioctl+0x4b/0x6f
system_call_fastpath+0x16/0x1b
thaw D ffff88013870d890 0 1352 1351 0x00000004
...
Call Trace:
rwsem_down_failed_common+0xdb/0x10f
call_rwsem_down_write_failed+0x13/0x20
down_write+0x25/0x27
thaw_super+0x13/0x9e
do_vfs_ioctl+0x1f5/0x490
vm_mmap_pgoff+0x76/0x87
sys_ioctl+0x4b/0x6f
filp_close+0x64/0x6c
system_call_fastpath+0x16/0x1b
where the thaw ioctl deadlocked at thaw_super() when called while chcp was
waiting at nilfs_transaction_begin() called from
nilfs_ioctl_change_cpmode(). This deadlock is 100% reproducible.
This is because nilfs_ioctl_change_cpmode() first locks sb->s_umount in
read mode and then waits for unfreezing in nilfs_transaction_begin(),
whereas thaw_super() locks sb->s_umount in write mode. The locking of
sb->s_umount here was intended to make snapshot mounts and the downgrade
of snapshots to checkpoints exclusive.
This fixes the deadlock issue by replacing the sb->s_umount usage in
nilfs_ioctl_change_cpmode() with a dedicated mutex which protects snapshot
mounts.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Tested-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The checkpoint deletion ioctl (rmcp ioctl) has potential for breaking
snapshot because it is not fully exclusive with checkpoint mode change
ioctl (chcp ioctl).
The rmcp ioctl first tests if the specified checkpoint is a snapshot or
not within nilfs_cpfile_delete_checkpoint function, and then calls
nilfs_cpfile_delete_checkpoints function to actually invalidate the
checkpoint only if it's not a snapshot. However, the checkpoint can be
changed into a snapshot by the chcp ioctl between these two operations.
In that case, calling nilfs_cpfile_delete_checkpoints() wrongly
invalidates the snapshot, which leads to snapshot list corruption and
snapshot count mismatch.
This fixes the issue by changing nilfs_cpfile_delete_checkpoints() so
that it reconfirms the target checkpoints are snapshot or not.
This second check is exclusive with the chcp operation since it is
protected by an existing semaphore.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
On minix2 and minix3 usually max_size is 7fffffff and the check in
question prohibits creation of last block spanning right before 7fffffff,
due to downward rounding during the division. Fix it by using
multiplication instead.
[akpm@linux-foundation.org: fix up code layout, use local `sb']
Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fixes the following checkpatch warnings:
WARNING: Use #include <linux/uaccess.h> instead of <asm/uaccess.h>
WARNING: Use #include <linux/io.h> instead of <asm/io.h>
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When the driver detects that the clock time is invalid, it attempts to
write a sane time into the hardware. We curently assume that everything
is OK if those writes succeeded. But it is better to re-read the time
from the hardware to ensure that the new settings got there OK.
Cc: Devendra Naga <devendra.aaru@gmail.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Anatolij Gustschin <agust@denx.de>
Cc: Andreas Dumberger <andreas.dumberger@tqs.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Akinobu Mita
Andrew Morton
Huang Shijie
Djalal Harouni
Jovi Zhang
Tetsuo Handa
Steven J. Magnani
Namjae Jeon
Vyacheslav Dubeyko
Ryusuke Konishi
Fernando Luis Vazquez Cao
Vladimir Serbinenko
Nick Bowler
Devendra Naga
Uwe Kleine-König
Sachin Kamat