Re: possible deadlock in lock_trace (3)
From: syzbot
Date: Mon Mar 16 2020 - 03:26:17 EST
syzbot has found a reproducer for the following crash on:
HEAD commit: a42a7bb6 Merge tag 'irq-urgent-2020-03-15' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1237321de00000
kernel config: https://syzkaller.appspot.com/x/.config?x=c2e311dba9a02ba9
dashboard link: https://syzkaller.appspot.com/bug?extid=985c8a3c7f3668d31a49
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1185f753e00000
IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+985c8a3c7f3668d31a49@xxxxxxxxxxxxxxxxxxxxxxxxx
overlayfs: './file0' not a directory
======================================================
WARNING: possible circular locking dependency detected
5.6.0-rc5-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.3/11170 is trying to acquire lock:
ffff888097db9c50 (&sig->cred_guard_mutex){+.+.}, at: lock_trace+0x45/0xe0 fs/proc/base.c:408
but task is already holding lock:
ffff8880913eebe0 (&p->lock){+.+.}, at: seq_read+0x6b/0x1160 fs/seq_file.c:161
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #3 (&p->lock){+.+.}:
__mutex_lock_common kernel/locking/mutex.c:956 [inline]
__mutex_lock+0x156/0x13c0 kernel/locking/mutex.c:1103
seq_read+0x6b/0x1160 fs/seq_file.c:161
do_loop_readv_writev fs/read_write.c:714 [inline]
do_loop_readv_writev fs/read_write.c:701 [inline]
do_iter_read+0x47f/0x650 fs/read_write.c:935
vfs_readv+0xf0/0x160 fs/read_write.c:1053
kernel_readv fs/splice.c:365 [inline]
default_file_splice_read+0x4fb/0xa20 fs/splice.c:422
do_splice_to+0x10e/0x160 fs/splice.c:892
splice_direct_to_actor+0x307/0x980 fs/splice.c:971
do_splice_direct+0x1a8/0x270 fs/splice.c:1080
do_sendfile+0x549/0xc40 fs/read_write.c:1520
__do_sys_sendfile64 fs/read_write.c:1581 [inline]
__se_sys_sendfile64 fs/read_write.c:1567 [inline]
__x64_sys_sendfile64+0x1cc/0x210 fs/read_write.c:1567
do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe
-> #2 (sb_writers#4){.+.+}:
percpu_down_read include/linux/percpu-rwsem.h:40 [inline]
__sb_start_write+0x21b/0x430 fs/super.c:1674
sb_start_write include/linux/fs.h:1650 [inline]
mnt_want_write+0x3a/0xb0 fs/namespace.c:354
ovl_setattr+0xdd/0x8b0 fs/overlayfs/inode.c:27
notify_change+0xb6d/0x1060 fs/attr.c:336
do_truncate+0x134/0x1f0 fs/open.c:64
handle_truncate fs/namei.c:3083 [inline]
do_last fs/namei.c:3496 [inline]
path_openat+0x291f/0x32b0 fs/namei.c:3607
do_filp_open+0x192/0x260 fs/namei.c:3637
do_sys_openat2+0x54c/0x740 fs/open.c:1146
do_sys_open+0xc3/0x140 fs/open.c:1162
do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe
-> #1 (&ovl_i_mutex_key[depth]){+.+.}:
down_write+0x8d/0x150 kernel/locking/rwsem.c:1534
inode_lock include/linux/fs.h:792 [inline]
process_measurement+0x68a/0x1740 security/integrity/ima/ima_main.c:230
ima_file_check+0xb9/0x100 security/integrity/ima/ima_main.c:442
do_last fs/namei.c:3494 [inline]
path_openat+0x127f/0x32b0 fs/namei.c:3607
do_filp_open+0x192/0x260 fs/namei.c:3637
do_open_execat+0x122/0x600 fs/exec.c:860
__do_execve_file.isra.0+0x16d5/0x2270 fs/exec.c:1765
do_execveat_common fs/exec.c:1871 [inline]
do_execve fs/exec.c:1888 [inline]
__do_sys_execve fs/exec.c:1964 [inline]
__se_sys_execve fs/exec.c:1959 [inline]
__x64_sys_execve+0x8a/0xb0 fs/exec.c:1959
do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe
-> #0 (&sig->cred_guard_mutex){+.+.}:
check_prev_add kernel/locking/lockdep.c:2475 [inline]
check_prevs_add kernel/locking/lockdep.c:2580 [inline]
validate_chain kernel/locking/lockdep.c:2970 [inline]
__lock_acquire+0x201b/0x3ca0 kernel/locking/lockdep.c:3954
lock_acquire+0x197/0x420 kernel/locking/lockdep.c:4484
__mutex_lock_common kernel/locking/mutex.c:956 [inline]
__mutex_lock+0x156/0x13c0 kernel/locking/mutex.c:1103
lock_trace+0x45/0xe0 fs/proc/base.c:408
proc_pid_personality+0x17/0xc0 fs/proc/base.c:3052
proc_single_show+0xf7/0x1c0 fs/proc/base.c:758
seq_read+0x4b9/0x1160 fs/seq_file.c:229
do_loop_readv_writev fs/read_write.c:714 [inline]
do_loop_readv_writev fs/read_write.c:701 [inline]
do_iter_read+0x47f/0x650 fs/read_write.c:935
vfs_readv+0xf0/0x160 fs/read_write.c:1053
kernel_readv fs/splice.c:365 [inline]
default_file_splice_read+0x4fb/0xa20 fs/splice.c:422
do_splice_to+0x10e/0x160 fs/splice.c:892
splice_direct_to_actor+0x307/0x980 fs/splice.c:971
do_splice_direct+0x1a8/0x270 fs/splice.c:1080
do_sendfile+0x549/0xc40 fs/read_write.c:1520
__do_sys_sendfile64 fs/read_write.c:1581 [inline]
__se_sys_sendfile64 fs/read_write.c:1567 [inline]
__x64_sys_sendfile64+0x1cc/0x210 fs/read_write.c:1567
do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe
other info that might help us debug this:
Chain exists of:
&sig->cred_guard_mutex --> sb_writers#4 --> &p->lock
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&p->lock);
lock(sb_writers#4);
lock(&p->lock);
lock(&sig->cred_guard_mutex);
*** DEADLOCK ***
2 locks held by syz-executor.3/11170:
#0: ffff88809fa24428 (sb_writers#13){.+.+}, at: file_start_write include/linux/fs.h:2904 [inline]
#0: ffff88809fa24428 (sb_writers#13){.+.+}, at: do_sendfile+0x939/0xc40 fs/read_write.c:1519
#1: ffff8880913eebe0 (&p->lock){+.+.}, at: seq_read+0x6b/0x1160 fs/seq_file.c:161
stack backtrace:
CPU: 0 PID: 11170 Comm: syz-executor.3 Not tainted 5.6.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x188/0x20d lib/dump_stack.c:118
check_noncircular+0x32e/0x3e0 kernel/locking/lockdep.c:1808
check_prev_add kernel/locking/lockdep.c:2475 [inline]
check_prevs_add kernel/locking/lockdep.c:2580 [inline]
validate_chain kernel/locking/lockdep.c:2970 [inline]
__lock_acquire+0x201b/0x3ca0 kernel/locking/lockdep.c:3954
lock_acqu