====================================================== WARNING: possible circular locking dependency detected 4.14.182-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.0/24086 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 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_rename+0x145/0xd90 fs/overlayfs/dir.c:935 vfs_rename+0x55a/0x1590 fs/namei.c:4496 SYSC_renameat2 fs/namei.c:4644 [inline] SyS_renameat2+0x8ad/0xa20 fs/namei.c:4533 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] lookup_slow+0x129/0x400 fs/namei.c:1674 walk_component+0x6a1/0xbc0 fs/namei.c:1825 link_path_walk+0x80a/0x1080 fs/namei.c:2154 path_openat+0x167/0x2aa0 fs/namei.c:3568 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_stack+0x10b/0x240 fs/proc/base.c:457 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.0/24086: #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: 24086 Comm: syz-executor.0 Not tainted 4.14.182-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 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x45ca69 RSP: 002b:00007f2d1a44bc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 00000000004fc580 RCX: 000000000045ca69 RDX: 0000000000000000 RSI: 0000000000000005 RDI: 0000000000000004 RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 4000000000010046 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000008dc R14: 00000000004cba56 R15: 00007f2d1a44c6d4 audit: type=1804 audit(1590940417.805:157): pid=24104 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="invalid_pcr" cause="open_writers" comm="syz-executor.1" name="/root/syzkaller-testdir777998400/syzkaller.Zlw13A/1325/file0" dev="sda1" ino=15931 res=1 audit: type=1804 audit(1590940417.835:158): pid=24099 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="invalid_pcr" cause="open_writers" comm="syz-executor.1" name="/root/syzkaller-testdir777998400/syzkaller.Zlw13A/1325/file0" dev="sda1" ino=15931 res=1 audit: type=1804 audit(1590940419.865:159): pid=24133 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="invalid_pcr" cause="open_writers" comm="syz-executor.1" name="/root/syzkaller-testdir777998400/syzkaller.Zlw13A/1326/file0" dev="sda1" ino=16148 res=1 audit: type=1804 audit(1590940419.875:160): pid=24141 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-testdir158633253/syzkaller.z8QFfz/1517/bus" dev="sda1" ino=16257 res=1 audit: type=1804 audit(1590940419.895:161): pid=24144 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="invalid_pcr" cause="open_writers" comm="syz-executor.1" name="/root/syzkaller-testdir777998400/syzkaller.Zlw13A/1327/file0" dev="sda1" ino=16369 res=1 audit: type=1804 audit(1590940419.935:162): pid=24152 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="invalid_pcr" cause="open_writers" comm="syz-executor.1" name="/root/syzkaller-testdir777998400/syzkaller.Zlw13A/1328/file0" dev="sda1" ino=16388 res=1 audit: type=1804 audit(1590940419.955:163): pid=24154 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="invalid_pcr" cause="open_writers" comm="syz-executor.1" name="/root/syzkaller-testdir777998400/syzkaller.Zlw13A/1329/file0" dev="sda1" ino=16052 res=1 audit: type=1804 audit(1590940420.685:164): pid=24149 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="invalid_pcr" cause="ToMToU" comm="syz-executor.5" name="/root/syzkaller-testdir158633253/syzkaller.z8QFfz/1517/bus" dev="sda1" ino=16257 res=1 audit: type=1804 audit(1590940420.685:165): pid=24181 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="invalid_pcr" cause="ToMToU" comm="syz-executor.5" name="/root/syzkaller-testdir158633253/syzkaller.z8QFfz/1517/bus" dev="sda1" ino=16257 res=1 audit: type=1804 audit(1590940420.685:166): pid=24149 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-testdir158633253/syzkaller.z8QFfz/1517/bus" dev="sda1" ino=16257 res=1 kauditd_printk_skb: 1 callbacks suppressed audit: type=1804 audit(1590940422.905:168): pid=24206 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-testdir158633253/syzkaller.z8QFfz/1519/bus" dev="sda1" ino=16722 res=1 audit: type=1804 audit(1590940423.115:169): pid=24229 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="invalid_pcr" cause="open_writers" comm="syz-executor.1" name="/root/syzkaller-testdir777998400/syzkaller.Zlw13A/1337/bus" dev="sda1" ino=16738 res=1 audit: type=1804 audit(1590940425.925:170): pid=24257 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="invalid_pcr" cause="open_writers" comm="syz-executor.1" name="/root/syzkaller-testdir777998400/syzkaller.Zlw13A/1338/bus" dev="sda1" ino=17013 res=1 audit: type=1804 audit(1590940425.935:171): pid=24251 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-testdir158633253/syzkaller.z8QFfz/1520/bus" dev="sda1" ino=16978 res=1