====================================================== WARNING: possible circular locking dependency detected 4.14.176-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.0/27514 is trying to acquire lock: (&sig->cred_guard_mutex){+.+.}, at: [] lock_trace+0x3f/0xc0 fs/proc/base.c:407 but task is already holding lock: (&p->lock){+.+.}, at: [] seq_read+0xba/0x1160 fs/seq_file.c:165 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&p->lock){+.+.}: __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 -> #2 (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 -> #1 (&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 -> #0 (&sig->cred_guard_mutex){+.+.}: 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 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+0x4d2/0x1160 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 other info that might help us debug this: Chain exists of: &sig->cred_guard_mutex --> sb_writers#3 --> &p->lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&p->lock); lock(sb_writers#3); lock(&p->lock); lock(&sig->cred_guard_mutex); *** DEADLOCK *** 1 lock held by syz-executor.0/27514: #0: (&p->lock){+.+.}, at: [] seq_read+0xba/0x1160 fs/seq_file.c:165 stack backtrace: CPU: 1 PID: 27514 Comm: syz-executor.0 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 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+0x4d2/0x1160 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 RIP: 0033:0x45c889 RSP: 002b:00007f80bbb04c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000127 RAX: ffffffffffffffda RBX: 00007f80bbb056d4 RCX: 000000000045c889 RDX: 000000000000037d RSI: 0000000020000500 RDI: 0000000000000007 RBP: 000000000076c0e0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 000000000000085c R14: 00000000004cb214 R15: 000000000076c0ec audit: type=1800 audit(1587215449.270:454): pid=27513 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="collect_data" cause="failed(directio)" comm="syz-executor.4" name="file0" dev="sda1" ino=16158 res=0 audit: type=1800 audit(1587215449.430:455): pid=27539 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="collect_data" cause="failed(directio)" comm="syz-executor.1" name="file0" dev="sda1" ino=16291 res=0 audit: type=1800 audit(1587215449.440:456): pid=27538 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="collect_data" cause="failed(directio)" comm="syz-executor.4" name="file0" dev="sda1" ino=16322 res=0 audit: type=1804 audit(1587215449.510:457): pid=27545 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="invalid_pcr" cause="ToMToU" comm="syz-executor.0" name="/root/syzkaller-testdir929285696/syzkaller.VcB94h/1657/file0" dev="sda1" ino=16369 res=1 audit: type=1804 audit(1587215449.520:458): pid=27545 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="invalid_pcr" cause="open_writers" comm="syz-executor.0" name="/root/syzkaller-testdir929285696/syzkaller.VcB94h/1657/file0" dev="sda1" ino=16369 res=1 audit: type=1804 audit(1587215449.540:459): pid=27547 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="invalid_pcr" cause="ToMToU" comm="syz-executor.0" name="/root/syzkaller-testdir929285696/syzkaller.VcB94h/1657/file0" dev="sda1" ino=16369 res=1 audit: type=1804 audit(1587215449.570:460): pid=27546 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="invalid_pcr" cause="open_writers" comm="syz-executor.3" name="/root/syzkaller-testdir255740828/syzkaller.KC3vxk/1557/bus" dev="sda1" ino=16370 res=1 audit: type=1804 audit(1587215449.590:461): pid=27546 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="invalid_pcr" cause="open_writers" comm="syz-executor.3" name="/root/syzkaller-testdir255740828/syzkaller.KC3vxk/1557/bus" dev="sda1" ino=16370 res=1 audit: type=1804 audit(1587215449.730:462): pid=27561 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="invalid_pcr" cause="ToMToU" comm="syz-executor.0" name="/root/syzkaller-testdir929285696/syzkaller.VcB94h/1658/file0" dev="sda1" ino=16327 res=1 audit: type=1804 audit(1587215449.750:463): pid=27561 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="invalid_pcr" cause="open_writers" comm="syz-executor.0" name="/root/syzkaller-testdir929285696/syzkaller.VcB94h/1658/file0" dev="sda1" ino=16327 res=1 netlink: 28 bytes leftover after parsing attributes in process `syz-executor.5'. netlink: 28 bytes leftover after parsing attributes in process `syz-executor.5'. selinux_nlmsg_perm: 7 callbacks suppressed SELinux: unrecognized netlink message: protocol=0 nlmsg_type=1018 sclass=netlink_route_socket pig=27638 comm=syz-executor.1 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=1018 sclass=netlink_route_socket pig=27676 comm=syz-executor.1 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=1018 sclass=netlink_route_socket pig=27722 comm=syz-executor.1 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=1018 sclass=netlink_route_socket pig=27741 comm=syz-executor.1 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=1018 sclass=netlink_route_socket pig=27756 comm=syz-executor.1 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=1018 sclass=netlink_route_socket pig=27763 comm=syz-executor.1 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=1018 sclass=netlink_route_socket pig=27773 comm=syz-executor.1 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=1018 sclass=netlink_route_socket pig=27787 comm=syz-executor.1 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=1018 sclass=netlink_route_socket pig=27794 comm=syz-executor.1 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=1018 sclass=netlink_route_socket pig=27802 comm=syz-executor.1 kauditd_printk_skb: 25 callbacks suppressed audit: type=1800 audit(1587215455.040:489): pid=27882 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="collect_data" cause="failed(directio)" comm="syz-executor.4" name="file0" dev="sda1" ino=17072 res=0 IPv6: ADDRCONF(NETDEV_CHANGE): vcan0: link becomes ready audit: type=1800 audit(1587215455.220:490): pid=27913 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="collect_data" cause="failed(directio)" comm="syz-executor.4" name="file0" dev="sda1" ino=15961 res=0 IPv6: ADDRCONF(NETDEV_CHANGE): vxcan0: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): vxcan1: link becomes ready audit: type=1800 audit(1587215455.340:491): pid=27932 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="collect_data" cause="failed(directio)" comm="syz-executor.4" name="file0" dev="sda1" ino=16188 res=0 audit: type=1800 audit(1587215455.500:492): pid=27946 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="collect_data" cause="failed(directio)" comm="syz-executor.4" name="file0" dev="sda1" ino=17072 res=0 audit: type=1800 audit(1587215456.080:493): pid=27971 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="collect_data" cause="failed(directio)" comm="syz-executor.4" name="file0" dev="sda1" ino=16201 res=0 IPv6: ADDRCONF(NETDEV_CHANGE): vcan0: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): vxcan0: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): vxcan1: link becomes ready audit: type=1800 audit(1587215456.360:494): pid=28008 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="collect_data" cause="failed(directio)" comm="syz-executor.4" name="file0" dev="sda1" ino=15960 res=0 selinux_nlmsg_perm: 79 callbacks suppressed SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket pig=28016 comm=syz-executor.3 audit: type=1800 audit(1587215457.000:495): pid=28022 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="collect_data" cause="failed(directio)" comm="syz-executor.4" name="file0" dev="sda1" ino=17099 res=0 netlink: 28 bytes leftover after parsing attributes in process `syz-executor.5'. audit: type=1800 audit(1587215457.090:496): pid=28035 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="collect_data" cause="failed(directio)" comm="syz-executor.4" name="file0" dev="sda1" ino=17091 res=0 netlink: 28 bytes leftover after parsing attributes in process `syz-executor.5'. audit: type=1800 audit(1587215457.890:497): pid=28072 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="collect_data" cause="failed(directio)" comm="syz-executor.4" name="file0" dev="sda1" ino=17108 res=0 audit: type=1800 audit(1587215458.020:498): pid=28090 uid=0 auid=0 ses=4 subj=system_u:system_r:kernel_t:s0 op="collect_data" cause="failed(directio)" comm="syz-executor.4" name="file0" dev="sda1" ino=17113 res=0