Hello, syzbot found the following crash on: HEAD commit: 63623fd4 Merge tag 'for-linus' of git://git.kernel.org/pub.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=17345181e00000 kernel config: https://syzkaller.appspot.com/x/.config?x=5d2e033af114153f dashboard link: https://syzkaller.appspot.com/bug?extid=d9ae59d4662c941e39c6 compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1374670de00000 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+d9ae59d4662c941e39c6@xxxxxxxxxxxxxxxxxxxxxxxxx ====================================================== WARNING: possible circular locking dependency detected 5.6.0-rc3-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.0/9659 is trying to acquire lock: ffff88807bd9dc90 (&sig->cred_guard_mutex){+.+.}, at: lock_trace fs/proc/base.c:408 [inline] ffff88807bd9dc90 (&sig->cred_guard_mutex){+.+.}, at: proc_pid_personality+0x4f/0x110 fs/proc/base.c:3052 but task is already holding lock: ffff88808b48d640 (&p->lock){+.+.}, at: seq_read+0x6b/0xdb0 fs/seq_file.c:161 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&p->lock){+.+.}: lock_acquire+0x154/0x250 kernel/locking/lockdep.c:4484 __mutex_lock_common+0x16e/0x2f30 kernel/locking/mutex.c:956 __mutex_lock kernel/locking/mutex.c:1103 [inline] mutex_lock_nested+0x1b/0x30 kernel/locking/mutex.c:1118 seq_read+0x6b/0xdb0 fs/seq_file.c:161 do_loop_readv_writev fs/read_write.c:714 [inline] do_iter_read+0x4a2/0x5b0 fs/read_write.c:935 vfs_readv+0xc2/0x120 fs/read_write.c:1053 kernel_readv fs/splice.c:365 [inline] default_file_splice_read+0x579/0xa40 fs/splice.c:422 do_splice_to fs/splice.c:892 [inline] splice_direct_to_actor+0x3c9/0xb90 fs/splice.c:971 do_splice_direct+0x200/0x330 fs/splice.c:1080 do_sendfile+0x7e4/0xfd0 fs/read_write.c:1520 __do_sys_sendfile64 fs/read_write.c:1581 [inline] __se_sys_sendfile64 fs/read_write.c:1567 [inline] __x64_sys_sendfile64+0x176/0x1b0 fs/read_write.c:1567 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #2 (sb_writers#3){.+.+}: lock_acquire+0x154/0x250 kernel/locking/lockdep.c:4484 percpu_down_read include/linux/percpu-rwsem.h:40 [inline] __sb_start_write+0x189/0x420 fs/super.c:1674 sb_start_write include/linux/fs.h:1649 [inline] mnt_want_write+0x4a/0xa0 fs/namespace.c:354 ovl_want_write+0x77/0x80 fs/overlayfs/util.c:21 ovl_setattr+0x55/0x790 fs/overlayfs/inode.c:27 notify_change+0xb6e/0xfb0 fs/attr.c:336 do_truncate+0x194/0x230 fs/open.c:64 handle_truncate fs/namei.c:3083 [inline] do_last fs/namei.c:3496 [inline] path_openat+0x271d/0x4380 fs/namei.c:3607 do_filp_open+0x192/0x3d0 fs/namei.c:3637 do_sys_openat2+0x42b/0x6f0 fs/open.c:1149 do_sys_open fs/open.c:1165 [inline] ksys_open include/linux/syscalls.h:1386 [inline] __do_sys_creat fs/open.c:1233 [inline] __se_sys_creat fs/open.c:1231 [inline] __x64_sys_creat+0xd5/0x100 fs/open.c:1231 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #1 (&ovl_i_mutex_key[depth]){+.+.}: lock_acquire+0x154/0x250 kernel/locking/lockdep.c:4484 down_write+0x57/0x140 kernel/locking/rwsem.c:1534 inode_lock include/linux/fs.h:791 [inline] process_measurement+0x2d7/0x18d0 security/integrity/ima/ima_main.c:230 ima_file_check+0x9b/0xe0 security/integrity/ima/ima_main.c:442 do_last fs/namei.c:3494 [inline] path_openat+0x1def/0x4380 fs/namei.c:3607 do_filp_open+0x192/0x3d0 fs/namei.c:3637 do_open_execat+0xff/0x620 fs/exec.c:860 __do_execve_file+0x758/0x1ca0 fs/exec.c:1765 do_execveat_common fs/exec.c:1871 [inline] do_execve fs/exec.c:1888 [inline] __do_sys_execve fs/exec.c:1964 [inline] __se_sys_execve fs/exec.c:1959 [inline] __x64_sys_execve+0x94/0xb0 fs/exec.c:1959 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&sig->cred_guard_mutex){+.+.}: check_prev_add kernel/locking/lockdep.c:2475 [inline] check_prevs_add kernel/locking/lockdep.c:2580 [inline] validate_chain+0x1507/0x7be0 kernel/locking/lockdep.c:2970 __lock_acquire+0xc5a/0x1bc0 kernel/locking/lockdep.c:3954 lock_acquire+0x154/0x250 kernel/locking/lockdep.c:4484 __mutex_lock_common+0x16e/0x2f30 kernel/locking/mutex.c:956 __mutex_lock kernel/locking/mutex.c:1103 [inline] mutex_lock_killable_nested+0x1b/0x30 kernel/locking/mutex.c:1133 lock_trace fs/proc/base.c:408 [inline] proc_pid_personality+0x4f/0x110 fs/proc/base.c:3052 proc_single_show+0xe7/0x180 fs/proc/base.c:758 seq_read+0x4d8/0xdb0 fs/seq_file.c:229 do_loop_readv_writev fs/read_write.c:714 [inline] do_iter_read+0x4a2/0x5b0 fs/read_write.c:935 vfs_readv+0xc2/0x120 fs/read_write.c:1053 kernel_readv fs/splice.c:365 [inline] default_file_splice_read+0x579/0xa40 fs/splice.c:422 do_splice_to fs/splice.c:892 [inline] splice_direct_to_actor+0x3c9/0xb90 fs/splice.c:971 do_splice_direct+0x200/0x330 fs/splice.c:1080 do_sendfile+0x7e4/0xfd0 fs/read_write.c:1520 __do_sys_sendfile64 fs/read_write.c:1581 [inline] __se_sys_sendfile64 fs/read_write.c:1567 [inline] __x64_sys_sendfile64+0x176/0x1b0 fs/read_write.c:1567 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 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.0/9659: #0: ffff88807b422428 (sb_writers#12){.+.+}, at: file_start_write include/linux/fs.h:2903 [inline] #0: ffff88807b422428 (sb_writers#12){.+.+}, at: do_sendfile+0x7c2/0xfd0 fs/read_write.c:1519 #1: ffff88808b48d640 (&p->lock){+.+.}, at: seq_read+0x6b/0xdb0 fs/seq_file.c:161 stack backtrace: CPU: 0 PID: 9659 Comm: syz-executor.0 Not tainted 5.6.0-rc3-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+0x1fb/0x318 lib/dump_stack.c:118 print_circular_bug+0xc3f/0xe70 kernel/locking/lockdep.c:1684 check_noncircular+0x206/0x3a0 kernel/locking/lockdep.c:1808 check_prev_add kernel/locking/lockdep.c:2475 [inline] check_prevs_add kernel/locking/lockdep.c:2580 [inline] validate_chain+0x1507/0x7be0 kernel/locking/lockdep.c:2970 __lock_acquire+0xc5a/0x1bc0 kernel/locking/lockdep.c:3954 lock_acquire+0x154/0x250 kernel/locking/lockdep.c:4484 __mutex_lock_common+0x16e/0x2f30 kernel/locking/mutex.c:956 __mutex_lock kernel/locking/mutex.c:1103 [inline] mutex_lock_killable_nested+0x1b/0x30 kernel/locking/mutex.c:1133 lock_trace fs/proc/base.c:408 [inline] proc_pid_personality+0x4f/0x110 fs/proc/base.c:3052 proc_single_show+0xe7/0x180 fs/proc/base.c:758 seq_read+0x4d8/0xdb0 fs/seq_file.c:229 do_loop_readv_writev fs/read_write.c:714 [inline] do_iter_read+0x4a2/0x5b0 fs/read_write.c:935 vfs_readv+0xc2/0x120 fs/read_write.c:1053 kernel_readv fs/splice.c:365 [inline] default_file_splice_read+0x579/0xa40 fs/splice.c:422 do_splice_to fs/splice.c:892 [inline] splice_direct_to_actor+0x3c9/0xb90 fs/splice.c:971 do_splice_direct+0x200/0x330 fs/splice.c:1080 do_sendfile+0x7e4/0xfd0 fs/read_write.c:1520 __do_sys_sendfile64 fs/read_write.c:1581 [inline] __se_sys_sendfile64 fs/read_write.c:1567 [inline] __x64_sys_sendfile64+0x176/0x1b0 fs/read_write.c:1567 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45c479 Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f853eeaac78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 00007f853eeab6d4 RCX: 000000000045c479 RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000003 RBP: 000000000076bfc0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000283 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000008d1 R14: 00000000004cb364 R15: 000000000076bfcc --- This bug is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. syzbot will keep track of this bug report. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. syzbot can test patches for this bug, for details see: https://goo.gl/tpsmEJ#testing-patches
