====================================================== WARNING: possible circular locking dependency detected 4.19.109-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.0/27423 is trying to acquire lock: 00000000bc2dcee2 (&sig->cred_guard_mutex){+.+.}, at: do_io_accounting+0x1da/0x7b0 fs/proc/base.c:2738 but task is already holding lock: 000000008b035951 (&p->lock){+.+.}, at: seq_read+0x6b/0x10f0 fs/seq_file.c:161 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&p->lock){+.+.}: seq_read+0x6b/0x10f0 fs/seq_file.c:161 proc_reg_read+0x1bd/0x280 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+0x46b/0x640 fs/read_write.c:925 vfs_readv+0xf0/0x160 fs/read_write.c:987 kernel_readv fs/splice.c:362 [inline] default_file_splice_read+0x478/0x970 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+0x1a8/0x270 fs/splice.c:1068 do_sendfile+0x549/0xc10 fs/read_write.c:1447 __do_sys_sendfile64 fs/read_write.c:1508 [inline] __se_sys_sendfile64 fs/read_write.c:1494 [inline] __x64_sys_sendfile64+0x1cc/0x210 fs/read_write.c:1494 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #2 (sb_writers#4){.+.+}: sb_start_write include/linux/fs.h:1578 [inline] mnt_want_write+0x3a/0xb0 fs/namespace.c:360 ovl_create_object+0x96/0x290 fs/overlayfs/dir.c:600 lookup_open+0x11f6/0x19b0 fs/namei.c:3235 do_last fs/namei.c:3327 [inline] path_openat+0x13cb/0x4200 fs/namei.c:3537 do_filp_open+0x1a1/0x280 fs/namei.c:3567 do_sys_open+0x3c0/0x500 fs/open.c:1088 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #1 (&ovl_i_mutex_dir_key[depth]){++++}: inode_lock_shared include/linux/fs.h:757 [inline] lookup_slow+0x43/0x70 fs/namei.c:1688 walk_component+0x70a/0x1ee0 fs/namei.c:1811 lookup_last fs/namei.c:2274 [inline] path_lookupat.isra.0+0x1f5/0x8d0 fs/namei.c:2319 filename_lookup+0x1b0/0x410 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:8572 perf_try_init_event+0x124/0x2e0 kernel/events/core.c:9845 perf_init_event kernel/events/core.c:9876 [inline] perf_event_alloc.part.0+0x1e5f/0x2f90 kernel/events/core.c:10150 perf_event_alloc kernel/events/core.c:10520 [inline] __do_sys_perf_event_open+0x902/0x2830 kernel/events/core.c:10621 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&sig->cred_guard_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0xf7/0x1300 kernel/locking/mutex.c:1072 do_io_accounting+0x1da/0x7b0 fs/proc/base.c:2738 proc_single_show+0xeb/0x170 fs/proc/base.c:755 seq_read+0x4b9/0x10f0 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+0x46b/0x640 fs/read_write.c:925 vfs_readv+0xf0/0x160 fs/read_write.c:987 do_preadv+0x1b6/0x270 fs/read_write.c:1071 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: &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 *** 1 lock held by syz-executor.0/27423: #0: 000000008b035951 (&p->lock){+.+.}, at: seq_read+0x6b/0x10f0 fs/seq_file.c:161 stack backtrace: CPU: 1 PID: 27423 Comm: syz-executor.0 Not tainted 4.19.109-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 print_circular_bug.isra.0.cold+0x1c4/0x282 kernel/locking/lockdep.c:1221 check_prev_add kernel/locking/lockdep.c:1861 [inline] check_prevs_add kernel/locking/lockdep.c:1974 [inline] validate_chain kernel/locking/lockdep.c:2415 [inline] __lock_acquire+0x2e19/0x49c0 kernel/locking/lockdep.c:3411 lock_acquire+0x170/0x400 kernel/locking/lockdep.c:3903 __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0xf7/0x1300 kernel/locking/mutex.c:1072 do_io_accounting+0x1da/0x7b0 fs/proc/base.c:2738 proc_single_show+0xeb/0x170 fs/proc/base.c:755 seq_read+0x4b9/0x10f0 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+0x46b/0x640 fs/read_write.c:925 vfs_readv+0xf0/0x160 fs/read_write.c:987 do_preadv+0x1b6/0x270 fs/read_write.c:1071 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45c849 Code: ad b6 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 b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f7cc71ffc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000127 RAX: ffffffffffffffda RBX: 00007f7cc72006d4 RCX: 000000000045c849 RDX: 00000000000003da RSI: 00000000200017c0 RDI: 0000000000000003 RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000857 R14: 00000000004cb187 R15: 000000000076bf0c input: syz0 as /devices/virtual/input/input17 audit: type=1800 audit(1584209157.278:109): pid=27588 uid=0 auid=4294967295 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 op=collect_data cause=failed comm="syz-executor.0" name="bus" dev="sda1" ino=16774 res=0 input: syz0 as /devices/virtual/input/input18 input: syz0 as /devices/virtual/input/input19 netlink: 36 bytes leftover after parsing attributes in process `syz-executor.2'. netlink: 36 bytes leftover after parsing attributes in process `syz-executor.2'. netlink: 36 bytes leftover after parsing attributes in process `syz-executor.2'. netlink: 36 bytes leftover after parsing attributes in process `syz-executor.2'. netlink: 36 bytes leftover after parsing attributes in process `syz-executor.2'. netlink: 36 bytes leftover after parsing attributes in process `syz-executor.2'. netlink: 36 bytes leftover after parsing attributes in process `syz-executor.2'. netlink: 36 bytes leftover after parsing attributes in process `syz-executor.2'. netlink: 36 bytes leftover after parsing attributes in process `syz-executor.2'. netlink: 36 bytes leftover after parsing attributes in process `syz-executor.2'. nla_parse: 7 callbacks suppressed netlink: 36 bytes leftover after parsing attributes in process `syz-executor.2'. netlink: 36 bytes leftover after parsing attributes in process `syz-executor.2'.