====================================================== WARNING: possible circular locking dependency detected 4.14.181-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.1/20361 is trying to acquire lock: (&p->lock){+.+.}, at: [] seq_read+0xba/0x1130 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+0x82e/0xaf0 fs/read_write.c:1440 x_tables: ip6_tables: eui64 match: used from hooks OUTPUT, but only valid from PREROUTING/INPUT/FORWARD 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_create_object+0x75/0x1d0 fs/overlayfs/dir.c:538 lookup_open+0x756/0x1700 fs/namei.c:3241 do_last fs/namei.c:3334 [inline] path_openat+0xddf/0x2aa0 fs/namei.c:3569 do_filp_open+0x18e/0x250 fs/namei.c:3603 do_sys_open+0x292/0x3e0 fs/open.c:1081 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb -> #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+0x148c/0x2aa0 fs/namei.c:3569 do_filp_open+0x18e/0x250 fs/namei.c:3603 do_open_execat+0xda/0x440 fs/exec.c:849 do_execveat_common.isra.0+0x680/0x1c50 fs/exec.c:1742 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+0x46/0xbb -> #1 (&sig->cred_guard_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xe8/0x1430 kernel/locking/mutex.c:893 lock_trace+0x3f/0xc0 fs/proc/base.c:407 proc_pid_syscall+0x81/0x1f0 fs/proc/base.c:639 proc_single_show+0xe7/0x150 fs/proc/base.c:761 seq_read+0x4d2/0x1130 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+0x46/0xbb -> #0 (&p->lock){+.+.}: lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xe8/0x1430 kernel/locking/mutex.c:893 seq_read+0xba/0x1130 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+0x46/0xbb 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.1/20361: #0: (sb_writers#3){.+.+}, at: [] file_start_write include/linux/fs.h:2708 [inline] #0: (sb_writers#3){.+.+}, at: [] do_sendfile+0x82e/0xaf0 fs/read_write.c:1440 stack backtrace: CPU: 0 PID: 20361 Comm: syz-executor.1 Not tainted 4.14.181-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+0x1b2/0x283 lib/dump_stack.c:58 print_circular_bug.isra.0.cold+0x2dc/0x425 kernel/locking/lockdep.c:1258 check_prev_add kernel/locking/lockdep.c:1905 [inline] check_prevs_add kernel/locking/lockdep.c:2022 [inline] validate_chain kernel/locking/lockdep.c:2464 [inline] __lock_acquire+0x3057/0x42a0 kernel/locking/lockdep.c:3491 lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xe8/0x1430 kernel/locking/mutex.c:893 seq_read+0xba/0x1130 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 x_tables: ip6_tables: eui64 match: used from hooks OUTPUT, but only valid from PREROUTING/INPUT/FORWARD do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x45ca29 RSP: 002b:00007f03071c4c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 00000000004fc540 RCX: 000000000045ca29 RDX: 0000000000000000 RSI: 0000000000000007 RDI: 0000000000000006 RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 4000000000010046 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000008dc R14: 00000000004cba16 R15: 00007f03071c56d4 netlink: 24 bytes leftover after parsing attributes in process `syz-executor.1'. x_tables: ip6_tables: eui64 match: used from hooks OUTPUT, but only valid from PREROUTING/INPUT/FORWARD netlink: 24 bytes leftover after parsing attributes in process `syz-executor.1'. audit: type=1400 audit(1590568848.377:64): avc: denied { create } for pid=20380 comm="syz-executor.2" scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=dccp_socket permissive=1 audit: type=1400 audit(1590568848.397:65): avc: denied { name_bind } for pid=20380 comm="syz-executor.2" src=20000 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:port_t:s0 tclass=dccp_socket permissive=1 audit: type=1400 audit(1590568848.397:66): avc: denied { name_connect } for pid=20380 comm="syz-executor.2" dest=20000 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:port_t:s0 tclass=dccp_socket permissive=1 x_tables: ip6_tables: eui64 match: used from hooks OUTPUT, but only valid from PREROUTING/INPUT/FORWARD x_tables: ip6_tables: eui64 match: used from hooks OUTPUT, but only valid from PREROUTING/INPUT/FORWARD x_tables: ip6_tables: eui64 match: used from hooks OUTPUT, but only valid from PREROUTING/INPUT/FORWARD x_tables: ip6_tables: eui64 match: used from hooks OUTPUT, but only valid from PREROUTING/INPUT/FORWARD x_tables: ip6_tables: eui64 match: used from hooks OUTPUT, but only valid from PREROUTING/INPUT/FORWARD x_tables: ip6_tables: eui64 match: used from hooks OUTPUT, but only valid from PREROUTING/INPUT/FORWARD x_tables: ip6_tables: eui64 match: used from hooks OUTPUT, but only valid from PREROUTING/INPUT/FORWARD x_tables: ip6_tables: eui64 match: used from hooks OUTPUT, but only valid from PREROUTING/INPUT/FORWARD x_tables: ip6_tables: eui64 match: used from hooks OUTPUT, but only valid from PREROUTING/INPUT/FORWARD x_tables: ip6_tables: eui64 match: used from hooks OUTPUT, but only valid from PREROUTING/INPUT/FORWARD x_tables: ip6_tables: eui64 match: used from hooks OUTPUT, but only valid from PREROUTING/INPUT/FORWARD x_tables: ip6_tables: eui64 match: used from hooks OUTPUT, but only valid from PREROUTING/INPUT/FORWARD x_tables: ip6_tables: eui64 match: used from hooks OUTPUT, but only valid from PREROUTING/INPUT/FORWARD x_tables: ip6_tables: eui64 match: used from hooks OUTPUT, but only valid from PREROUTING/INPUT/FORWARD x_tables: ip6_tables: eui64 match: used from hooks OUTPUT, but only valid from PREROUTING/INPUT/FORWARD x_tables: ip6_tables: eui64 match: used from hooks OUTPUT, but only valid from PREROUTING/INPUT/FORWARD x_tables: ip6_tables: eui64 match: used from hooks OUTPUT, but only valid from PREROUTING/INPUT/FORWARD IPVS: length: 101 != 8 IPVS: length: 101 != 8 IPVS: length: 101 != 8 IPVS: length: 101 != 8 x_tables: ip6_tables: eui64 match: used from hooks OUTPUT, but only valid from PREROUTING/INPUT/FORWARD x_tables: ip6_tables: eui64 match: used from hooks OUTPUT, but only valid from PREROUTING/INPUT/FORWARD