From: syzbot <syzbot+a55ccfc8a853d3cff213@syzkaller.appspotmail.com>
To: amir73il@gmail.com, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-unionfs@vger.kernel.org,
miklos@szeredi.hu, syzkaller-bugs@googlegroups.com,
viro@zeniv.linux.org.uk
Subject: Re: possible deadlock in path_openat
Date: Thu, 18 Apr 2019 22:25:04 -0700 [thread overview]
Message-ID: <00000000000057eb510586db5717@google.com> (raw)
In-Reply-To: <00000000000044cbf80576baaecd@google.com>
syzbot has found a reproducer for the following crash on:
HEAD commit: 3f018f4a Add linux-next specific files for 20190418
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=128f767b200000
kernel config: https://syzkaller.appspot.com/x/.config?x=faa7bdc352fc157e
dashboard link: https://syzkaller.appspot.com/bug?extid=a55ccfc8a853d3cff213
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14fb9457200000
IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+a55ccfc8a853d3cff213@syzkaller.appspotmail.com
======================================================
WARNING: possible circular locking dependency detected
5.1.0-rc5-next-20190418 #28 Not tainted
------------------------------------------------------
syz-executor.0/8098 is trying to acquire lock:
000000006bd07a6a (&ovl_i_mutex_dir_key[depth]#2){++++}, at:
inode_lock_shared include/linux/fs.h:782 [inline]
000000006bd07a6a (&ovl_i_mutex_dir_key[depth]#2){++++}, at: do_last
fs/namei.c:3321 [inline]
000000006bd07a6a (&ovl_i_mutex_dir_key[depth]#2){++++}, at:
path_openat+0x1e98/0x46e0 fs/namei.c:3533
but task is already holding lock:
0000000046f9863b (&sig->cred_guard_mutex){+.+.}, at: prepare_bprm_creds
fs/exec.c:1407 [inline]
0000000046f9863b (&sig->cred_guard_mutex){+.+.}, at:
__do_execve_file.isra.0+0x376/0x23f0 fs/exec.c:1750
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #4 (&sig->cred_guard_mutex){+.+.}:
lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4200
__mutex_lock_common kernel/locking/mutex.c:925 [inline]
__mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1072
mutex_lock_killable_nested+0x16/0x20 kernel/locking/mutex.c:1102
do_io_accounting+0x1f4/0x830 fs/proc/base.c:2739
proc_tgid_io_accounting+0x23/0x30 fs/proc/base.c:2788
proc_single_show+0xf6/0x170 fs/proc/base.c:743
seq_read+0x4db/0x1130 fs/seq_file.c:229
do_loop_readv_writev fs/read_write.c:701 [inline]
do_loop_readv_writev fs/read_write.c:688 [inline]
do_iter_read+0x4a9/0x660 fs/read_write.c:922
vfs_readv+0xf0/0x160 fs/read_write.c:984
kernel_readv fs/splice.c:358 [inline]
default_file_splice_read+0x475/0x890 fs/splice.c:413
do_splice_to+0x12a/0x190 fs/splice.c:876
do_splice+0x110b/0x1420 fs/splice.c:1183
__do_sys_splice fs/splice.c:1424 [inline]
__se_sys_splice fs/splice.c:1404 [inline]
__x64_sys_splice+0x2c6/0x330 fs/splice.c:1404
do_syscall_64+0x103/0x670 arch/x86/entry/common.c:298
entry_SYSCALL_64_after_hwframe+0x49/0xbe
-> #3 (&p->lock){+.+.}:
lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4200
__mutex_lock_common kernel/locking/mutex.c:925 [inline]
__mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1072
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087
seq_read+0x71/0x1130 fs/seq_file.c:161
proc_reg_read+0x1fe/0x2c0 fs/proc/inode.c:227
do_loop_readv_writev fs/read_write.c:701 [inline]
do_loop_readv_writev fs/read_write.c:688 [inline]
do_iter_read+0x4a9/0x660 fs/read_write.c:922
vfs_readv+0xf0/0x160 fs/read_write.c:984
kernel_readv fs/splice.c:358 [inline]
default_file_splice_read+0x475/0x890 fs/splice.c:413
do_splice_to+0x12a/0x190 fs/splice.c:876
do_splice+0x110b/0x1420 fs/splice.c:1183
__do_sys_splice fs/splice.c:1424 [inline]
__se_sys_splice fs/splice.c:1404 [inline]
__x64_sys_splice+0x2c6/0x330 fs/splice.c:1404
do_syscall_64+0x103/0x670 arch/x86/entry/common.c:298
entry_SYSCALL_64_after_hwframe+0x49/0xbe
-> #2 (&pipe->mutex/1){+.+.}:
lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4200
__mutex_lock_common kernel/locking/mutex.c:925 [inline]
__mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1072
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087
pipe_lock_nested fs/pipe.c:62 [inline]
pipe_lock+0x6e/0x80 fs/pipe.c:70
iter_file_splice_write+0x18b/0xbe0 fs/splice.c:696
do_splice_from fs/splice.c:847 [inline]
do_splice+0x70a/0x1420 fs/splice.c:1154
__do_sys_splice fs/splice.c:1424 [inline]
__se_sys_splice fs/splice.c:1404 [inline]
__x64_sys_splice+0x2c6/0x330 fs/splice.c:1404
do_syscall_64+0x103/0x670 arch/x86/entry/common.c:298
entry_SYSCALL_64_after_hwframe+0x49/0xbe
-> #1 (sb_writers#5){.+.+}:
lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4200
percpu_down_read include/linux/percpu-rwsem.h:36 [inline]
__sb_start_write+0x20b/0x360 fs/super.c:1613
sb_start_write include/linux/fs.h:1621 [inline]
mnt_want_write+0x3f/0xc0 fs/namespace.c:358
ovl_want_write+0x76/0xa0 fs/overlayfs/util.c:24
ovl_do_remove+0xe9/0xd70 fs/overlayfs/dir.c:840
ovl_rmdir+0x1b/0x20 fs/overlayfs/dir.c:890
vfs_rmdir fs/namei.c:3878 [inline]
vfs_rmdir+0x19c/0x470 fs/namei.c:3857
do_rmdir+0x39e/0x420 fs/namei.c:3939
__do_sys_rmdir fs/namei.c:3957 [inline]
__se_sys_rmdir fs/namei.c:3955 [inline]
__x64_sys_rmdir+0x36/0x40 fs/namei.c:3955
do_syscall_64+0x103/0x670 arch/x86/entry/common.c:298
entry_SYSCALL_64_after_hwframe+0x49/0xbe
-> #0 (&ovl_i_mutex_dir_key[depth]#2){++++}:
check_prevs_add kernel/locking/lockdep.c:2322 [inline]
validate_chain kernel/locking/lockdep.c:2703 [inline]
__lock_acquire+0x239c/0x3fb0 kernel/locking/lockdep.c:3690
lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4200
down_read+0x3f/0x1a0 kernel/locking/rwsem.c:24
inode_lock_shared include/linux/fs.h:782 [inline]
do_last fs/namei.c:3321 [inline]
path_openat+0x1e98/0x46e0 fs/namei.c:3533
do_filp_open+0x1a1/0x280 fs/namei.c:3563
do_open_execat+0x137/0x690 fs/exec.c:856
__do_execve_file.isra.0+0x178d/0x23f0 fs/exec.c:1758
do_execveat_common fs/exec.c:1865 [inline]
do_execve fs/exec.c:1882 [inline]
__do_sys_execve fs/exec.c:1958 [inline]
__se_sys_execve fs/exec.c:1953 [inline]
__x64_sys_execve+0x8f/0xc0 fs/exec.c:1953
do_syscall_64+0x103/0x670 arch/x86/entry/common.c:298
entry_SYSCALL_64_after_hwframe+0x49/0xbe
other info that might help us debug this:
Chain exists of:
&ovl_i_mutex_dir_key[depth]#2 --> &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(&ovl_i_mutex_dir_key[depth]#2);
*** DEADLOCK ***
1 lock held by syz-executor.0/8098:
#0: 0000000046f9863b (&sig->cred_guard_mutex){+.+.}, at:
prepare_bprm_creds fs/exec.c:1407 [inline]
#0: 0000000046f9863b (&sig->cred_guard_mutex){+.+.}, at:
__do_execve_file.isra.0+0x376/0x23f0 fs/exec.c:1750
stack backtrace:
CPU: 0 PID: 8098 Comm: syz-executor.0 Not tainted 5.1.0-rc5-next-20190418
#28
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+0x172/0x1f0 lib/dump_stack.c:113
print_circular_bug.isra.0.cold+0x1cc/0x28f kernel/locking/lockdep.c:1560
check_prev_add.constprop.0+0xf11/0x23c0 kernel/locking/lockdep.c:2209
check_prevs_add kernel/locking/lockdep.c:2322 [inline]
validate_chain kernel/locking/lockdep.c:2703 [inline]
__lock_acquire+0x239c/0x3fb0 kernel/locking/lockdep.c:3690
lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4200
down_read+0x3f/0x1a0 kernel/locking/rwsem.c:24
inode_lock_shared include/linux/fs.h:782 [inline]
do_last fs/namei.c:3321 [inline]
path_openat+0x1e98/0x46e0 fs/namei.c:3533
do_filp_open+0x1a1/0x280 fs/namei.c:3563
do_open_execat+0x137/0x690 fs/exec.c:856
__do_execve_file.isra.0+0x178d/0x23f0 fs/exec.c:1758
do_execveat_common fs/exec.c:1865 [inline]
do_execve fs/exec.c:1882 [inline]
__do_sys_execve fs/exec.c:1958 [inline]
__se_sys_execve fs/exec.c:1953 [inline]
__x64_sys_execve+0x8f/0xc0 fs/exec.c:1953
do_syscall_64+0x103/0x670 arch/x86/entry/common.c:298
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x458c29
Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
ff 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f5db8befc78 EFLAGS: 00000246 ORIG_RAX: 000000000000003b
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000458c29
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000000
RBP: 000000000073bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f5db8bf06d4
R13: 00000000004bf216 R14: 00000000004d0458 R15: 00000000ffffffff
next prev parent reply other threads:[~2019-04-19 5:25 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-25 23:44 possible deadlock in path_openat syzbot
2018-09-26 4:33 ` Miklos Szeredi
2018-09-27 6:05 ` Amir Goldstein
2018-09-27 6:36 ` Miklos Szeredi
2018-09-27 8:26 ` Amir Goldstein
2019-04-19 5:25 ` syzbot [this message]
2019-04-19 5:31 ` syzbot
2019-11-18 2:14 ` syzbot
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=00000000000057eb510586db5717@google.com \
--to=syzbot+a55ccfc8a853d3cff213@syzkaller.appspotmail.com \
--cc=amir73il@gmail.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-unionfs@vger.kernel.org \
--cc=miklos@szeredi.hu \
--cc=syzkaller-bugs@googlegroups.com \
--cc=viro@zeniv.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.