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Message-ID: <001a113bb44672e783055f8787a3@google.com>
Date: Mon, 04 Dec 2017 10:03:01 -0800
From: syzbot
<bot+e6aa4df2569624fc2b37ff61b464f38c3440bb04@...kaller.appspotmail.com>
To: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
syzkaller-bugs@...glegroups.com, viro@...iv.linux.org.uk
Subject: possible deadlock in fifo_open
syzkaller has found reproducer for the following crash on
ae64f9bd1d3621b5e60d7363bc20afb46aede215
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/master
compiler: gcc (GCC) 7.1.1 20170620
.config is attached
Raw console output is attached.
C reproducer is attached
syzkaller reproducer is attached. See https://goo.gl/kgGztJ
for information about syzkaller reproducers
======================================================
WARNING: possible circular locking dependency detected
4.15.0-rc2+ #206 Not tainted
------------------------------------------------------
syzkaller022699/3086 is trying to acquire lock:
(&pipe->mutex/1){+.+.}, at: [<00000000698950dd>] __pipe_lock fs/pipe.c:88
[inline]
(&pipe->mutex/1){+.+.}, at: [<00000000698950dd>] fifo_open+0x15c/0xa40
fs/pipe.c:916
but task is already holding lock:
(&sig->cred_guard_mutex){+.+.}, at: [<0000000082fd15e8>]
prepare_bprm_creds+0x53/0x110 fs/exec.c:1390
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (&sig->cred_guard_mutex){+.+.}:
lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4004
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893
mutex_lock_killable_nested+0x16/0x20 kernel/locking/mutex.c:923
do_io_accounting+0x1c2/0xf50 fs/proc/base.c:2682
proc_tgid_io_accounting+0x22/0x30 fs/proc/base.c:2731
proc_single_show+0xf8/0x170 fs/proc/base.c:744
seq_read+0x385/0x13d0 fs/seq_file.c:234
__vfs_read+0xef/0xa00 fs/read_write.c:411
vfs_read+0x124/0x360 fs/read_write.c:447
SYSC_read fs/read_write.c:573 [inline]
SyS_read+0xef/0x220 fs/read_write.c:566
entry_SYSCALL_64_fastpath+0x1f/0x96
-> #1 (&p->lock){+.+.}:
lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4004
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
seq_read+0xd5/0x13d0 fs/seq_file.c:165
do_loop_readv_writev fs/read_write.c:673 [inline]
do_iter_read+0x3db/0x5b0 fs/read_write.c:897
vfs_readv+0x121/0x1c0 fs/read_write.c:959
kernel_readv fs/splice.c:361 [inline]
default_file_splice_read+0x508/0xae0 fs/splice.c:416
do_splice_to+0x110/0x170 fs/splice.c:880
do_splice fs/splice.c:1173 [inline]
SYSC_splice fs/splice.c:1402 [inline]
SyS_splice+0x11a8/0x1630 fs/splice.c:1382
entry_SYSCALL_64_fastpath+0x1f/0x96
-> #0 (&pipe->mutex/1){+.+.}:
check_prevs_add kernel/locking/lockdep.c:2031 [inline]
validate_chain kernel/locking/lockdep.c:2473 [inline]
__lock_acquire+0x3498/0x47f0 kernel/locking/lockdep.c:3500
lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4004
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
__pipe_lock fs/pipe.c:88 [inline]
fifo_open+0x15c/0xa40 fs/pipe.c:916
do_dentry_open+0x682/0xd70 fs/open.c:752
vfs_open+0x107/0x230 fs/open.c:866
do_last fs/namei.c:3379 [inline]
path_openat+0x1157/0x3530 fs/namei.c:3519
do_filp_open+0x25b/0x3b0 fs/namei.c:3554
do_open_execat+0x1b9/0x5c0 fs/exec.c:849
do_execveat_common.isra.30+0x90c/0x23c0 fs/exec.c:1741
do_execve fs/exec.c:1848 [inline]
SYSC_execve fs/exec.c:1929 [inline]
SyS_execve+0x39/0x50 fs/exec.c:1924
do_syscall_64+0x26c/0x920 arch/x86/entry/common.c:285
return_from_SYSCALL_64+0x0/0x75
other info that might help us debug this:
Chain exists of:
&pipe->mutex/1 --> &p->lock --> &sig->cred_guard_mutex
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&sig->cred_guard_mutex);
lock(&p->lock);
lock(&sig->cred_guard_mutex);
lock(&pipe->mutex/1);
*** DEADLOCK ***
1 lock held by syzkaller022699/3086:
#0: (&sig->cred_guard_mutex){+.+.}, at: [<0000000082fd15e8>]
prepare_bprm_creds+0x53/0x110 fs/exec.c:1390
stack backtrace:
CPU: 0 PID: 3086 Comm: syzkaller022699 Not tainted 4.15.0-rc2+ #206
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x194/0x257 lib/dump_stack.c:53
print_circular_bug+0x42d/0x610 kernel/locking/lockdep.c:1271
check_prev_add+0x666/0x15f0 kernel/locking/lockdep.c:1914
check_prevs_add kernel/locking/lockdep.c:2031 [inline]
validate_chain kernel/locking/lockdep.c:2473 [inline]
__lock_acquire+0x3498/0x47f0 kernel/locking/lockdep.c:3500
lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4004
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
__pipe_lock fs/pipe.c:88 [inline]
fifo_open+0x15c/0xa40 fs/pipe.c:916
do_dentry_open+0x682/0xd70 fs/open.c:752
vfs_open+0x107/0x230 fs/open.c:866
do_last fs/namei.c:3379 [inline]
path_openat+0x1157/0x3530 fs/namei.c:3519
do_filp_open+0x25b/0x3b0 fs/namei.c:3554
do_open_execat+0x1b9/0x5c0 fs/exec.c:849
do_execveat_common.isra.30+0x90c/0x23c0 fs/exec.c:1741
do_execve fs/exec.c:1848 [inline]
SYSC_execve fs/exec.c:1929 [inline]
SyS_execve+0x39/0x50 fs/exec.c:1924
do_syscall_64+0x26c/0x920 arch/x86/entry/common.c:285
entry_SYSCALL64_slow_path+0x25/0x25
RIP: 0033:0x440219
RSP: 002b:00007ffd9e4890b8 EFLAGS: 00000217 ORIG_RAX: 000000000000003b
RAX: ffffffffffffffda RBX: 0030656c69662f2e RCX: 0000000000440219
RDX: 0000000020324ff0 RSI: 0000000020a7bfc8 RDI: 0000000020f8aff8
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000001 R11: 0000000000000217 R12: 0000000000401ae0
R13: 0000000000401b70 R14: 0000000000000000 R15: 0000000000000000
View attachment "config.txt" of type "text/plain" (126531 bytes)
Download attachment "raw.log" of type "application/octet-stream" (9783 bytes)
View attachment "repro.txt" of type "text/plain" (770 bytes)
Download attachment "repro.c" of type "application/octet-stream" (1962 bytes)
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