possible deadlock in walk

possible deadlock in walk_component
Status: upstream: reported on 2020/07/06 08:23
Reported-by: syzbot+accdedfdaea55738ab96@syzkaller.appspotmail.com
First crash: 244d, last: 10d

similar bugs (1):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	possible deadlock in walk_component				11	157d	371d	0/21	auto-closed as invalid on 2021/01/29 13:43

Sample crash report:

======================================================
WARNING: possible circular locking dependency detected
4.19.177-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.2/10772 is trying to acquire lock:
000000008dfdcef4 (&ovl_i_mutex_dir_key[depth]){++++}, at: inode_lock_shared include/linux/fs.h:758 [inline]
000000008dfdcef4 (&ovl_i_mutex_dir_key[depth]){++++}, at: lookup_slow fs/namei.c:1688 [inline]
000000008dfdcef4 (&ovl_i_mutex_dir_key[depth]){++++}, at: walk_component+0x798/0xda0 fs/namei.c:1811

but task is already holding lock:
000000004004c566 (&sig->cred_guard_mutex){+.+.}, at: __do_sys_perf_event_open kernel/events/core.c:10616 [inline]
000000004004c566 (&sig->cred_guard_mutex){+.+.}, at: __se_sys_perf_event_open+0x18eb/0x2720 kernel/events/core.c:10525

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&sig->cred_guard_mutex){+.+.}:
       lock_trace fs/proc/base.c:402 [inline]
       proc_pid_syscall+0xb8/0x2f0 fs/proc/base.c:635
       proc_single_show+0xeb/0x170 fs/proc/base.c:755
       seq_read+0x4be/0x1160 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+0x471/0x630 fs/read_write.c:925
       vfs_readv+0xe5/0x150 fs/read_write.c:987
       do_preadv fs/read_write.c:1071 [inline]
       __do_sys_preadv fs/read_write.c:1121 [inline]
       __se_sys_preadv fs/read_write.c:1116 [inline]
       __x64_sys_preadv+0x22b/0x310 fs/read_write.c:1116
       do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #2 (&p->lock){+.+.}:
       seq_read+0x6b/0x1160 fs/seq_file.c:161
       proc_reg_read+0x1bd/0x2d0 fs/proc/inode.c:231
       do_loop_readv_writev fs/read_write.c:701 [inline]
       do_loop_readv_writev fs/read_write.c:688 [inline]
       do_iter_read+0x471/0x630 fs/read_write.c:925
       vfs_readv+0xe5/0x150 fs/read_write.c:987
       kernel_readv fs/splice.c:362 [inline]
       default_file_splice_read+0x457/0xa00 fs/splice.c:417
       do_splice_to+0x10e/0x160 fs/splice.c:881
       splice_direct_to_actor+0x2b9/0x8d0 fs/splice.c:959
       do_splice_direct+0x1a7/0x270 fs/splice.c:1068
       do_sendfile+0x550/0xc30 fs/read_write.c:1447
       __do_sys_sendfile64 fs/read_write.c:1508 [inline]
       __se_sys_sendfile64+0x147/0x160 fs/read_write.c:1494
       do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #1 (sb_writers#3){.+.+}:
       sb_start_write include/linux/fs.h:1579 [inline]
       mnt_want_write+0x3a/0xb0 fs/namespace.c:360
       ovl_do_remove+0xf0/0xdb0 fs/overlayfs/dir.c:843
       vfs_rmdir.part.0+0x10f/0x3d0 fs/namei.c:3882
       vfs_rmdir fs/namei.c:3868 [inline]
       do_rmdir+0x3fd/0x490 fs/namei.c:3943
       do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #0 (&ovl_i_mutex_dir_key[depth]){++++}:
       down_read+0x36/0x80 kernel/locking/rwsem.c:24
       inode_lock_shared include/linux/fs.h:758 [inline]
       lookup_slow fs/namei.c:1688 [inline]
       walk_component+0x798/0xda0 fs/namei.c:1811
       link_path_walk.part.0+0x901/0x1230 fs/namei.c:2142
       link_path_walk fs/namei.c:2270 [inline]
       path_lookupat+0xe4/0x8d0 fs/namei.c:2318
       filename_lookup+0x1ac/0x5a0 fs/namei.c:2349
       create_local_trace_uprobe+0x82/0x490 kernel/trace/trace_uprobe.c:1356
       perf_uprobe_init+0x128/0x200 kernel/trace/trace_event_perf.c:317
       perf_uprobe_event_init+0xf8/0x190 kernel/events/core.c:8589
       perf_try_init_event+0x124/0x2e0 kernel/events/core.c:9860
       perf_init_event kernel/events/core.c:9891 [inline]
       perf_event_alloc.part.0+0x1b16/0x2eb0 kernel/events/core.c:10165
       perf_event_alloc kernel/events/core.c:10535 [inline]
       __do_sys_perf_event_open kernel/events/core.c:10636 [inline]
       __se_sys_perf_event_open+0x550/0x2720 kernel/events/core.c:10525
       do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

other info that might help us debug this:

Chain exists of:
  &ovl_i_mutex_dir_key[depth] --> &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]);

 *** DEADLOCK ***

2 locks held by syz-executor.2/10772:
 #0: 000000004004c566 (&sig->cred_guard_mutex){+.+.}, at: __do_sys_perf_event_open kernel/events/core.c:10616 [inline]
 #0: 000000004004c566 (&sig->cred_guard_mutex){+.+.}, at: __se_sys_perf_event_open+0x18eb/0x2720 kernel/events/core.c:10525
 #1: 00000000fdf0c7ee (&pmus_srcu){....}, at: perf_event_alloc.part.0+0xe6c/0x2eb0 kernel/events/core.c:10161

stack backtrace:
CPU: 1 PID: 10772 Comm: syz-executor.2 Not tainted 4.19.177-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+0x1fc/0x2ef lib/dump_stack.c:118
 print_circular_bug.constprop.0.cold+0x2d7/0x41e kernel/locking/lockdep.c:1221
 check_prev_add kernel/locking/lockdep.c:1865 [inline]
 check_prevs_add kernel/locking/lockdep.c:1978 [inline]
 validate_chain kernel/locking/lockdep.c:2419 [inline]
 __lock_acquire+0x30c9/0x3ff0 kernel/locking/lockdep.c:3415
 lock_acquire+0x170/0x3c0 kernel/locking/lockdep.c:3907
 down_read+0x36/0x80 kernel/locking/rwsem.c:24
 inode_lock_shared include/linux/fs.h:758 [inline]
 lookup_slow fs/namei.c:1688 [inline]
 walk_component+0x798/0xda0 fs/namei.c:1811
 link_path_walk.part.0+0x901/0x1230 fs/namei.c:2142
 link_path_walk fs/namei.c:2270 [inline]
 path_lookupat+0xe4/0x8d0 fs/namei.c:2318
 filename_lookup+0x1ac/0x5a0 fs/namei.c:2349
 create_local_trace_uprobe+0x82/0x490 kernel/trace/trace_uprobe.c:1356
 perf_uprobe_init+0x128/0x200 kernel/trace/trace_event_perf.c:317
 perf_uprobe_event_init+0xf8/0x190 kernel/events/core.c:8589
 perf_try_init_event+0x124/0x2e0 kernel/events/core.c:9860
 perf_init_event kernel/events/core.c:9891 [inline]
 perf_event_alloc.part.0+0x1b16/0x2eb0 kernel/events/core.c:10165
 perf_event_alloc kernel/events/core.c:10535 [inline]
 __do_sys_perf_event_open kernel/events/core.c:10636 [inline]
 __se_sys_perf_event_open+0x550/0x2720 kernel/events/core.c:10525
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x465ef9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fdbb9607188 EFLAGS: 00000246 ORIG_RAX: 000000000000012a
RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000465ef9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000180
RBP: 00000000004bcd1c R08: 0000000000000000 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000246 R12: 000000000056bf60
R13: 00007ffcd51a4b5f R14: 00007fdbb9607300 R15: 0000000000022000
netlink: 'syz-executor.0': attribute type 5 has an invalid length.
ldm_validate_partition_table(): Disk read failed.
Dev loop7: unable to read RDB block 0
 loop7: unable to read partition table
IPVS: ftp: loaded support on port[0] = 21
ldm_validate_partition_table(): Disk read failed.
IPVS: ftp: loaded support on port[0] = 21
Dev loop7: unable to read RDB block 0
 loop7: unable to read partition table
IPVS: ftp: loaded support on port[0] = 21
IPVS: ftp: loaded support on port[0] = 21
IPVS: ftp: loaded support on port[0] = 21
netlink: 24 bytes leftover after parsing attributes in process `syz-executor.4'.
netlink: 24 bytes leftover after parsing attributes in process `syz-executor.4'.
IPVS: ftp: loaded support on port[0] = 21
kvm [11106]: vcpu0, guest rIP: 0x14c disabled perfctr wrmsr: 0x186 data 0x1
gfs2: not a GFS2 filesystem
kvm [11106]: vcpu0, guest rIP: 0x14c disabled perfctr wrmsr: 0x186 data 0x1
netlink: 24 bytes leftover after parsing attributes in process `syz-executor.3'.
kvm [11106]: vcpu0, guest rIP: 0x14c disabled perfctr wrmsr: 0x186 data 0x1
gfs2: not a GFS2 filesystem
kvm [11106]: vcpu0, guest rIP: 0x14c disabled perfctr wrmsr: 0x186 data 0x1
netlink: 24 bytes leftover after parsing attributes in process `syz-executor.3'.
kvm [11106]: vcpu0, guest rIP: 0x14c disabled perfctr wrmsr: 0x186 data 0x1
kvm [11106]: vcpu0, guest rIP: 0x14c disabled perfctr wrmsr: 0x186 data 0x1
gfs2: not a GFS2 filesystem
kvm [11106]: vcpu0, guest rIP: 0x14c disabled perfctr wrmsr: 0x186 data 0x1
kvm [11106]: vcpu0, guest rIP: 0x14c disabled perfctr wrmsr: 0x186 data 0x1
kvm [11106]: vcpu0, guest rIP: 0x14c disabled perfctr wrmsr: 0x186 data 0x1
kvm [11106]: vcpu0, guest rIP: 0x14c disabled perfctr wrmsr: 0x186 data 0x1
netlink: 24 bytes leftover after parsing attributes in process `syz-executor.3'.
gfs2: not a GFS2 filesystem
netlink: 24 bytes leftover after parsing attributes in process `syz-executor.3'.
gfs2: not a GFS2 filesystem
netlink: 24 bytes leftover after parsing attributes in process `syz-executor.3'.
netlink: 8 bytes leftover after parsing attributes in process `syz-executor.3'.
netlink: 8 bytes leftover after parsing attributes in process `syz-executor.3'.
netlink: 8 bytes leftover after parsing attributes in process `syz-executor.3'.
input: syz0 as /devices/virtual/input/input24
input: syz0 as /devices/virtual/input/input25
input: syz0 as /devices/virtual/input/input26

Crashes (29):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Title
ci2-linux-4-19	2021/02/25 15:18	linux-4.19.y	2d19be46	76f7fc95	.config	log	report	info	possible deadlock in walk_component
ci2-linux-4-19	2021/01/04 19:27	linux-4.19.y	3207316b	79264ae3	.config	log	report	info
ci2-linux-4-19	2020/12/27 14:21	linux-4.19.y	13d2ce42	2242f77f	.config	log	report	info
ci2-linux-4-19	2020/12/03 09:44	linux-4.19.y	daefdc9e	8c9190ef	.config	log	report	info
ci2-linux-4-19	2020/11/26 12:03	linux-4.19.y	0c88e405	2f1cec62	.config	log	report	info
ci2-linux-4-19	2020/10/20 08:11	linux-4.19.y	ad326970	ff4a3345	.config	log	report	info
ci2-linux-4-19	2020/10/11 14:33	linux-4.19.y	a1b977b4	4a77ae0b	.config	log	report	info
ci2-linux-4-19	2020/10/06 18:27	linux-4.19.y	b09c3451	1880b4a9	.config	log	report	info
ci2-linux-4-19	2020/10/01 22:51	linux-4.19.y	b09c3451	9602ddf4	.config	log	report	info
ci2-linux-4-19	2020/09/26 18:13	linux-4.19.y	10ad6cfd	2d5ea0cb	.config	log	report	info
ci2-linux-4-19	2020/09/25 00:08	linux-4.19.y	d09b8017	54289b08	.config	log	report	info
ci2-linux-4-19	2020/09/20 04:46	linux-4.19.y	015e94d0	53ce8104	.config	log	report	info
ci2-linux-4-19	2020/09/17 14:09	linux-4.19.y	a87f9628	8247808b	.config	log	report	info
ci2-linux-4-19	2020/09/07 11:23	linux-4.19.y	c37da90e	abf9ba4f	.config	log	report
ci2-linux-4-19	2020/09/07 11:06	linux-4.19.y	c37da90e	abf9ba4f	.config	log	report
ci2-linux-4-19	2020/09/07 05:40	linux-4.19.y	c37da90e	abf9ba4f	.config	log	report
ci2-linux-4-19	2020/09/06 20:46	linux-4.19.y	c37da90e	abf9ba4f	.config	log	report
ci2-linux-4-19	2020/09/06 02:33	linux-4.19.y	c37da90e	abf9ba4f	.config	log	report
ci2-linux-4-19	2020/09/04 21:09	linux-4.19.y	c37da90e	abf9ba4f	.config	log	report
ci2-linux-4-19	2020/09/01 21:48	linux-4.19.y	f6d5cb9e	abf9ba4f	.config	log	report
ci2-linux-4-19	2020/08/30 09:35	linux-4.19.y	f6d5cb9e	d5a3ae1f	.config	log	report
ci2-linux-4-19	2020/08/24 03:07	linux-4.19.y	d18b78ab	cef5ae68	.config	log	report
ci2-linux-4-19	2020/08/17 19:27	linux-4.19.y	c14d30dc	5ce13532	.config	log	report
ci2-linux-4-19	2020/08/12 11:36	linux-4.19.y	c14d30dc	0d7bd2e0	.config	log	report
ci2-linux-4-19	2020/08/04 10:58	linux-4.19.y	13af6c74	80a06902	.config	log	report
ci2-linux-4-19	2020/07/31 08:16	linux-4.19.y	205a42ce	8df85ed9	.config	log	report
ci2-linux-4-19	2020/07/28 13:56	linux-4.19.y	20b3a3df	cb93dc6a	.config	log	report
ci2-linux-4-19	2020/07/26 06:06	linux-4.19.y	20b3a3df	1f7cc1ca	.config	log	report
ci2-linux-4-19	2020/07/06 08:22	linux-4.19.y	399849e4	ac5a135b	.config	log	report