====================================================== WARNING: possible circular locking dependency detected 4.14.176-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.3/16168 is trying to acquire lock: (&p->lock){+.+.}, at: [] seq_read+0xba/0x1160 fs/seq_file.c:165 but task is already holding lock: (sb_writers#3){.+.+}, at: [] file_start_write include/linux/fs.h:2708 [inline] (sb_writers#3){.+.+}, at: [] do_sendfile+0x865/0xaf0 fs/read_write.c:1440 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (sb_writers#3){.+.+}: percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:36 [inline] percpu_down_read include/linux/percpu-rwsem.h:59 [inline] __sb_start_write+0x1a1/0x2e0 fs/super.c:1363 sb_start_write include/linux/fs.h:1549 [inline] mnt_want_write+0x3a/0xb0 fs/namespace.c:386 ovl_xattr_set+0x4d/0x270 fs/overlayfs/inode.c:214 ovl_posix_acl_xattr_set+0x3f9/0x830 fs/overlayfs/super.c:762 __vfs_setxattr+0xdc/0x130 fs/xattr.c:150 __vfs_setxattr_noperm+0xfd/0x3c0 fs/xattr.c:181 vfs_setxattr+0xba/0xe0 fs/xattr.c:224 setxattr+0x1a9/0x300 fs/xattr.c:453 path_setxattr+0x118/0x130 fs/xattr.c:472 SYSC_lsetxattr fs/xattr.c:494 [inline] SyS_lsetxattr+0x33/0x40 fs/xattr.c:490 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #2 (&ovl_i_mutex_dir_key[depth]){++++}: down_read+0x37/0xa0 kernel/locking/rwsem.c:24 inode_lock_shared include/linux/fs.h:729 [inline] do_last fs/namei.c:3333 [inline] path_openat+0x185a/0x3c50 fs/namei.c:3569 do_filp_open+0x18e/0x250 fs/namei.c:3603 do_open_execat+0xda/0x430 fs/exec.c:849 do_execveat_common.isra.0+0x694/0x1c70 fs/exec.c:1740 do_execve fs/exec.c:1847 [inline] SYSC_execve fs/exec.c:1928 [inline] SyS_execve+0x34/0x40 fs/exec.c:1923 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #1 (&sig->cred_guard_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893 do_io_accounting+0x1c7/0x750 fs/proc/base.c:2726 proc_single_show+0xe7/0x150 fs/proc/base.c:761 seq_read+0x4d2/0x1160 fs/seq_file.c:237 do_loop_readv_writev fs/read_write.c:695 [inline] do_loop_readv_writev fs/read_write.c:682 [inline] do_iter_read+0x3e3/0x5a0 fs/read_write.c:919 vfs_readv+0xd3/0x130 fs/read_write.c:981 do_preadv+0x161/0x200 fs/read_write.c:1065 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #0 (&p->lock){+.+.}: lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3994 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893 seq_read+0xba/0x1160 fs/seq_file.c:165 proc_reg_read+0xf2/0x160 fs/proc/inode.c:217 do_loop_readv_writev fs/read_write.c:695 [inline] do_loop_readv_writev fs/read_write.c:682 [inline] do_iter_read+0x3e3/0x5a0 fs/read_write.c:919 vfs_readv+0xd3/0x130 fs/read_write.c:981 kernel_readv fs/splice.c:361 [inline] default_file_splice_read+0x41d/0x870 fs/splice.c:416 do_splice_to+0xfb/0x150 fs/splice.c:880 splice_direct_to_actor+0x20a/0x730 fs/splice.c:952 do_splice_direct+0x164/0x210 fs/splice.c:1061 do_sendfile+0x469/0xaf0 fs/read_write.c:1441 SYSC_sendfile64 fs/read_write.c:1502 [inline] SyS_sendfile64+0xff/0x110 fs/read_write.c:1488 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 other info that might help us debug this: Chain exists of: &p->lock --> &ovl_i_mutex_dir_key[depth] --> sb_writers#3 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(sb_writers#3); lock(&ovl_i_mutex_dir_key[depth]); lock(sb_writers#3); lock(&p->lock); *** DEADLOCK *** 1 lock held by syz-executor.3/16168: #0: (sb_writers#3){.+.+}, at: [] file_start_write include/linux/fs.h:2708 [inline] #0: (sb_writers#3){.+.+}, at: [] do_sendfile+0x865/0xaf0 fs/read_write.c:1440 stack backtrace: CPU: 0 PID: 16168 Comm: syz-executor.3 Not tainted 4.14.176-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x13e/0x194 lib/dump_stack.c:58 print_circular_bug.isra.0.cold+0x1c4/0x282 kernel/locking/lockdep.c:1258 check_prev_add kernel/locking/lockdep.c:1901 [inline] check_prevs_add kernel/locking/lockdep.c:2018 [inline] validate_chain kernel/locking/lockdep.c:2460 [inline] __lock_acquire+0x2cb3/0x4620 kernel/locking/lockdep.c:3487 lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3994 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893 seq_read+0xba/0x1160 fs/seq_file.c:165 proc_reg_read+0xf2/0x160 fs/proc/inode.c:217 do_loop_readv_writev fs/read_write.c:695 [inline] do_loop_readv_writev fs/read_write.c:682 [inline] do_iter_read+0x3e3/0x5a0 fs/read_write.c:919 vfs_readv+0xd3/0x130 fs/read_write.c:981 kernel_readv fs/splice.c:361 [inline] default_file_splice_read+0x41d/0x870 fs/splice.c:416 do_splice_to+0xfb/0x150 fs/splice.c:880 splice_direct_to_actor+0x20a/0x730 fs/splice.c:952 do_splice_direct+0x164/0x210 fs/splice.c:1061 do_sendfile+0x469/0xaf0 fs/read_write.c:1441 SYSC_sendfile64 fs/read_write.c:1502 [inline] SyS_sendfile64+0xff/0x110 fs/read_write.c:1488 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45c889 RSP: 002b:00007fd270ba6c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 00007fd270ba76d4 RCX: 000000000045c889 RDX: 0000000000000000 RSI: 0000000000000008 RDI: 0000000000000006 RBP: 000000000076c0e0 R08: 0000000000000000 R09: 0000000000000000 R10: 4000000000010046 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000008d6 R14: 00000000004cb7ee R15: 000000000076c0ec xt_ecn: cannot match TCP bits in rule for non-tcp packets xt_ecn: cannot match TCP bits in rule for non-tcp packets xt_ecn: cannot match TCP bits in rule for non-tcp packets xt_ecn: cannot match TCP bits in rule for non-tcp packets netlink: 24 bytes leftover after parsing attributes in process `syz-executor.2'. netlink: 24 bytes leftover after parsing attributes in process `syz-executor.2'. netlink: 24 bytes leftover after parsing attributes in process `syz-executor.2'. netlink: 24 bytes leftover after parsing attributes in process `syz-executor.2'. audit: type=1800 audit(1587017142.163:213): pid=16349 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="collect_data" cause="failed(directio)" comm="syz-executor.5" name="file0" dev="sda1" ino=16762 res=0 audit: type=1804 audit(1587017142.183:214): pid=16349 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="invalid_pcr" cause="open_writers" comm="syz-executor.5" name="/root/syzkaller-testdir343222941/syzkaller.rhuTex/253/file0" dev="sda1" ino=16762 res=1 audit: type=1800 audit(1587017142.443:215): pid=16379 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="collect_data" cause="failed(directio)" comm="syz-executor.5" name="file0" dev="sda1" ino=16761 res=0 audit: type=1804 audit(1587017142.483:216): pid=16379 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="invalid_pcr" cause="open_writers" comm="syz-executor.5" name="/root/syzkaller-testdir343222941/syzkaller.rhuTex/254/file0" dev="sda1" ino=16761 res=1 audit: type=1800 audit(1587017142.643:217): pid=16400 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="collect_data" cause="failed(directio)" comm="syz-executor.5" name="file0" dev="sda1" ino=16757 res=0 audit: type=1804 audit(1587017142.673:218): pid=16400 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="invalid_pcr" cause="open_writers" comm="syz-executor.5" name="/root/syzkaller-testdir343222941/syzkaller.rhuTex/255/file0" dev="sda1" ino=16757 res=1 audit: type=1800 audit(1587017142.733:219): pid=16413 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="collect_data" cause="failed(directio)" comm="syz-executor.5" name="file0" dev="sda1" ino=16749 res=0 audit: type=1804 audit(1587017142.743:220): pid=16413 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="invalid_pcr" cause="open_writers" comm="syz-executor.5" name="/root/syzkaller-testdir343222941/syzkaller.rhuTex/256/file0" dev="sda1" ino=16749 res=1 xt_TPROXY: Can be used only in combination with either -p tcp or -p udp xt_TPROXY: Can be used only in combination with either -p tcp or -p udp xt_TPROXY: Can be used only in combination with either -p tcp or -p udp xt_TPROXY: Can be used only in combination with either -p tcp or -p udp