possible deadlock in lock_trace (2)

Status: auto-closed as invalid on 2019/10/25 08:41
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+4b7e4be91bb87d4158e5@syzkaller.appspotmail.com
First crash: 2659d, last: 2629d
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
possible deadlock in lock_trace (2) 0 (1) 2019/04/17 16:46
▶ ▼ Similar bugs (7)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 possible deadlock in lock_trace 4 syz error 42 2142d 2648d 0/1 upstream: reported syz repro on 2019/04/28 18:16
linux-4.14 possible deadlock in lock_trace 4 syz, C error 146 2200d 2657d 0/1 upstream: reported C repro on 2019/04/19 09:51
android-49 possible deadlock in lock_trace 4 syz, C 7424 2428d 2664d 0/3 public: reported C repro on 2019/04/12 00:00
upstream possible deadlock in lock_trace fs 4 syz, C 1847 2681d 3162d 0/29 closed as dup on 2017/12/12 21:59
upstream possible deadlock in lock_trace (3) fs 4 syz inconclusive done 69 2308d 2443d 15/29 fixed on 2020/08/18 22:40
android-414 possible deadlock in lock_trace 4 syz 203 2673d 2664d 0/1 public: reported syz repro on 2019/04/12 00:01
android-44 possible deadlock in lock_trace 4 syz, C 41 2435d 2665d 0/2 public: reported C repro on 2019/04/11 08:44

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
5.1.0-rc5+ #71 Not tainted
------------------------------------------------------
syz-executor.5/9344 is trying to acquire lock:
000000002573c5cd (&sig->cred_guard_mutex){+.+.}, at: lock_trace+0x4a/0xe0 fs/proc/base.c:388

but task is already holding lock:
00000000e68fae9b (&p->lock){+.+.}, at: seq_read+0x71/0x1130 fs/seq_file.c:161

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&p->lock){+.+.}:
       lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211
       __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
       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
       splice_direct_to_actor+0x2d2/0x970 fs/splice.c:953
       do_splice_direct+0x1da/0x2a0 fs/splice.c:1062
       do_sendfile+0x597/0xd00 fs/read_write.c:1443
       __do_sys_sendfile64 fs/read_write.c:1504 [inline]
       __se_sys_sendfile64 fs/read_write.c:1490 [inline]
       __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1490
       do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #2 (sb_writers#4){.+.+}:
       lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211
       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_rename+0x22b/0x1940 fs/overlayfs/dir.c:1079
       vfs_rename+0x803/0x1ac0 fs/namei.c:4475
       do_renameat2+0xb0f/0xc40 fs/namei.c:4625
       __do_sys_rename fs/namei.c:4671 [inline]
       __se_sys_rename fs/namei.c:4669 [inline]
       __x64_sys_rename+0x61/0x80 fs/namei.c:4669
       do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #1 (&ovl_i_mutex_dir_key[depth]){++++}:
       lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211
       down_read+0x3b/0x90 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+0x103/0x610 arch/x86/entry/common.c:290
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #0 (&sig->cred_guard_mutex){+.+.}:
       check_prevs_add kernel/locking/lockdep.c:2333 [inline]
       validate_chain kernel/locking/lockdep.c:2714 [inline]
       __lock_acquire+0x239c/0x3fb0 kernel/locking/lockdep.c:3701
       lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211
       __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
       lock_trace+0x4a/0xe0 fs/proc/base.c:388
       proc_pid_syscall+0x8a/0x220 fs/proc/base.c:623
       proc_single_show+0xf6/0x170 fs/proc/base.c:744
       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
       splice_direct_to_actor+0x2d2/0x970 fs/splice.c:953
       do_splice_direct+0x1da/0x2a0 fs/splice.c:1062
       do_sendfile+0x597/0xd00 fs/read_write.c:1443
       __do_sys_sendfile64 fs/read_write.c:1504 [inline]
       __se_sys_sendfile64 fs/read_write.c:1490 [inline]
       __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1490
       do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
       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.5/9344:
 #0: 000000003ef5ac57 (sb_writers#7){.+.+}, at: file_start_write include/linux/fs.h:2825 [inline]
 #0: 000000003ef5ac57 (sb_writers#7){.+.+}, at: do_sendfile+0x9b9/0xd00 fs/read_write.c:1442
 #1: 00000000e68fae9b (&p->lock){+.+.}, at: seq_read+0x71/0x1130 fs/seq_file.c:161

stack backtrace:
CPU: 0 PID: 9344 Comm: syz-executor.5 Not tainted 5.1.0-rc5+ #71
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:1571
 check_prev_add.constprop.0+0xf11/0x23c0 kernel/locking/lockdep.c:2220
 check_prevs_add kernel/locking/lockdep.c:2333 [inline]
 validate_chain kernel/locking/lockdep.c:2714 [inline]
 __lock_acquire+0x239c/0x3fb0 kernel/locking/lockdep.c:3701
 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211
 __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
 lock_trace+0x4a/0xe0 fs/proc/base.c:388
 proc_pid_syscall+0x8a/0x220 fs/proc/base.c:623
 proc_single_show+0xf6/0x170 fs/proc/base.c:744
 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
 splice_direct_to_actor+0x2d2/0x970 fs/splice.c:953
 do_splice_direct+0x1da/0x2a0 fs/splice.c:1062
 do_sendfile+0x597/0xd00 fs/read_write.c:1443
 __do_sys_sendfile64 fs/read_write.c:1504 [inline]
 __se_sys_sendfile64 fs/read_write.c:1490 [inline]
 __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1490
 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
 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:00007f9b470bec78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000458c29
RDX: 0000000000000000 RSI: 0000000000000005 RDI: 0000000000000004
RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000246 R12: 00007f9b470bf6d4
R13: 00000000004c5e10 R14: 00000000004da5c8 R15: 00000000ffffffff

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2019/04/17 03:04 upstream 444fe9913539 b0e8efcb .config console log report ci-upstream-kasan-gce-selinux-root
2019/05/17 15:22 linux-next b1d6682ef9bb 95dfd515 .config console log report ci-upstream-linux-next-kasan-gce-root
2019/05/12 06:19 linux-next a802303934b3 c017728b .config console log report ci-upstream-linux-next-kasan-gce-root
* Struck through repros no longer work on HEAD.