====================================================== WARNING: possible circular locking dependency detected 4.19.211-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.4/11631 is trying to acquire lock: 00000000f5ac0d67 (&sig->cred_guard_mutex){+.+.}, at: lock_trace fs/proc/base.c:402 [inline] 00000000f5ac0d67 (&sig->cred_guard_mutex){+.+.}, at: proc_pid_stack+0x160/0x350 fs/proc/base.c:452 but task is already holding lock: 00000000b83f11d7 (&p->lock){+.+.}, at: seq_read+0x6b/0x11c0 fs/seq_file.c:164 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&p->lock){+.+.}: seq_read+0x6b/0x11c0 fs/seq_file.c:164 proc_reg_read+0x1bd/0x2d0 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+0x471/0x630 fs/read_write.c:925 vfs_readv+0xe5/0x150 fs/read_write.c:987 kernel_readv fs/splice.c:362 [inline] default_file_splice_read+0x457/0xa00 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+0x1a7/0x270 fs/splice.c:1068 do_sendfile+0x550/0xc30 fs/read_write.c:1447 __do_sys_sendfile64 fs/read_write.c:1508 [inline] __se_sys_sendfile64+0x147/0x160 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#3){.+.+}: sb_start_write include/linux/fs.h:1579 [inline] mnt_want_write+0x3a/0xb0 fs/namespace.c:360 ovl_fix_origin fs/overlayfs/namei.c:796 [inline] ovl_lookup+0x1109/0x1a00 fs/overlayfs/namei.c:915 __lookup_slow+0x246/0x4a0 fs/namei.c:1672 lookup_slow fs/namei.c:1689 [inline] walk_component+0x7ac/0xda0 fs/namei.c:1811 lookup_last fs/namei.c:2274 [inline] path_lookupat+0x1ff/0x8d0 fs/namei.c:2319 filename_lookup+0x1ac/0x5a0 fs/namei.c:2349 user_path include/linux/namei.h:62 [inline] do_mount+0x147/0x2f50 fs/namespace.c:2762 ksys_mount+0xcf/0x130 fs/namespace.c:3038 __do_sys_mount fs/namespace.c:3052 [inline] __se_sys_mount fs/namespace.c:3049 [inline] __x64_sys_mount+0xba/0x150 fs/namespace.c:3049 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:758 [inline] do_last fs/namei.c:3326 [inline] path_openat+0x17ec/0x2df0 fs/namei.c:3537 do_filp_open+0x18c/0x3f0 fs/namei.c:3567 do_open_execat+0x11d/0x5b0 fs/exec.c:853 __do_execve_file+0x1a8b/0x2360 fs/exec.c:1770 do_execveat_common fs/exec.c:1879 [inline] do_execve+0x35/0x50 fs/exec.c:1896 __do_sys_execve fs/exec.c:1977 [inline] __se_sys_execve fs/exec.c:1972 [inline] __x64_sys_execve+0x7c/0xa0 fs/exec.c:1972 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:937 [inline] __mutex_lock+0xd7/0x1190 kernel/locking/mutex.c:1078 lock_trace fs/proc/base.c:402 [inline] proc_pid_stack+0x160/0x350 fs/proc/base.c:452 proc_single_show+0xeb/0x170 fs/proc/base.c:755 seq_read+0x4e0/0x11c0 fs/seq_file.c:232 __vfs_read+0xf7/0x750 fs/read_write.c:416 vfs_read+0x194/0x3c0 fs/read_write.c:452 ksys_read+0x12b/0x2a0 fs/read_write.c:579 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#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 *** 2 locks held by syz-executor.4/11631: #0: 00000000efff8cac (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x26f/0x310 fs/file.c:767 #1: 00000000b83f11d7 (&p->lock){+.+.}, at: seq_read+0x6b/0x11c0 fs/seq_file.c:164 stack backtrace: CPU: 1 PID: 11631 Comm: syz-executor.4 Not tainted 4.19.211-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+0x1fc/0x2ef lib/dump_stack.c:118 print_circular_bug.constprop.0.cold+0x2d7/0x41e kernel/locking/lockdep.c:1222 check_prev_add kernel/locking/lockdep.c:1866 [inline] check_prevs_add kernel/locking/lockdep.c:1979 [inline] validate_chain kernel/locking/lockdep.c:2420 [inline] __lock_acquire+0x30c9/0x3ff0 kernel/locking/lockdep.c:3416 lock_acquire+0x170/0x3c0 kernel/locking/lockdep.c:3908 __mutex_lock_common kernel/locking/mutex.c:937 [inline] __mutex_lock+0xd7/0x1190 kernel/locking/mutex.c:1078 lock_trace fs/proc/base.c:402 [inline] proc_pid_stack+0x160/0x350 fs/proc/base.c:452 proc_single_show+0xeb/0x170 fs/proc/base.c:755 seq_read+0x4e0/0x11c0 fs/seq_file.c:232 __vfs_read+0xf7/0x750 fs/read_write.c:416 vfs_read+0x194/0x3c0 fs/read_write.c:452 ksys_read+0x12b/0x2a0 fs/read_write.c:579 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7f4eda652cbc Code: ec 28 48 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 f9 fc ff ff 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 31 c0 0f 05 <48> 3d 00 f0 ff ff 77 34 44 89 c7 48 89 44 24 08 e8 2f fd ff ff 48 RSP: 002b:00007f4ed90150e0 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 0000000020002380 RCX: 00007f4eda652cbc RDX: 0000000000002000 RSI: 0000000020002380 RDI: 0000000000000003 RBP: 00007f4eda6fa0ad R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000003 R11: 0000000000000246 R12: 0000000020008c80 R13: 0000000000000003 R14: 00007f4ed9015300 R15: 0000000000022000 audit: type=1326 audit(1654840149.477:283): auid=4294967295 uid=0 gid=0 ses=4294967295 subj==unconfined pid=11753 comm="syz-executor.2" exe="/root/syz-executor.2" sig=31 arch=c000003e syscall=202 compat=0 ip=0x7fe9d06cf109 code=0x0 audit: type=1326 audit(1654840149.507:284): auid=4294967295 uid=0 gid=0 ses=4294967295 subj==unconfined pid=11752 comm="syz-executor.3" exe="/root/syz-executor.3" sig=31 arch=c000003e syscall=202 compat=0 ip=0x7f1efdead109 code=0x0 audit: type=1326 audit(1654840149.537:285): auid=4294967295 uid=0 gid=0 ses=4294967295 subj==unconfined pid=11782 comm="syz-executor.3" exe="/root/syz-executor.3" sig=31 arch=c000003e syscall=202 compat=0 ip=0x7f1efdead109 code=0x0 audit: type=1326 audit(1654840149.537:286): auid=4294967295 uid=0 gid=0 ses=4294967295 subj==unconfined pid=11783 comm="syz-executor.2" exe="/root/syz-executor.2" sig=31 arch=c000003e syscall=202 compat=0 ip=0x7fe9d06cf109 code=0x0 netlink: 4 bytes leftover after parsing attributes in process `syz-executor.5'. kauditd_printk_skb: 4 callbacks suppressed audit: type=1804 audit(1654840150.097:291): pid=11888 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.5" name="/root/syzkaller-testdir142491307/syzkaller.KAXl1G/1994/bus" dev="sda1" ino=14375 res=1 audit: type=1800 audit(1654840150.097:292): pid=11888 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="syz-executor.5" name="bus" dev="sda1" ino=14375 res=0 netlink: 12 bytes leftover after parsing attributes in process `syz-executor.3'. netlink: 4 bytes leftover after parsing attributes in process `syz-executor.3'. 8021q: adding VLAN 0 to HW filter on device batadv1 ucma_write: process 13570 (syz-executor.4) changed security contexts after opening file descriptor, this is not allowed. REISERFS warning (device loop3): sh-2012 read_super_block: found unknown format "73" of reiserfs with non-standard magic REISERFS warning (device loop3): sh-2006 read_super_block: bread failed (dev loop3, block 16, size 4096) REISERFS warning (device loop3): sh-2021 reiserfs_fill_super: can not find reiserfs on loop3 REISERFS warning (device loop3): sh-2012 read_super_block: found unknown format "73" of reiserfs with non-standard magic REISERFS warning (device loop3): sh-2006 read_super_block: bread failed (dev loop3, block 16, size 4096) REISERFS warning (device loop3): sh-2021 reiserfs_fill_super: can not find reiserfs on loop3 REISERFS warning (device loop3): sh-2012 read_super_block: found unknown format "73" of reiserfs with non-standard magic REISERFS warning (device loop3): sh-2006 read_super_block: bread failed (dev loop3, block 16, size 4096) REISERFS warning (device loop3): sh-2021 reiserfs_fill_super: can not find reiserfs on loop3 netlink: 512 bytes leftover after parsing attributes in process `syz-executor.5'. REISERFS warning (device loop3): sh-2012 read_super_block: found unknown format "73" of reiserfs with non-standard magic netlink: 512 bytes leftover after parsing attributes in process `syz-executor.5'. REISERFS warning (device loop3): sh-2006 read_super_block: bread failed (dev loop3, block 16, size 4096) REISERFS warning (device loop3): sh-2021 reiserfs_fill_super: can not find reiserfs on loop3 netlink: 512 bytes leftover after parsing attributes in process `syz-executor.5'. netlink: 512 bytes leftover after parsing attributes in process `syz-executor.5'. PM: Marking nosave pages: [mem 0x00000000-0x00000fff] PM: Marking nosave pages: [mem 0x0009f000-0x000fffff] PM: Marking nosave pages: [mem 0xbfffd000-0xffffffff] PM: Basic memory bitmaps created PM: Basic memory bitmaps freed