[CC linux-unionfs@] On Sun, Apr 14, 2019 at 6:06 PM syzbot <syzbot+5378878b09e052edef7f@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > Hello, > > syzbot found the following crash on: > > HEAD commit: bcb67f0f Add linux-next specific files for 20190412 > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=135b5e9f200000 > kernel config: https://syzkaller.appspot.com/x/.config?x=35c479ecf64ba753 > dashboard link: https://syzkaller.appspot.com/bug?extid=5378878b09e052edef7f > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > > Unfortunately, I don't have any reproducer for this crash yet. > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+5378878b09e052edef7f@xxxxxxxxxxxxxxxxxxxxxxxxx > > ====================================================== > WARNING: possible circular locking dependency detected > 5.1.0-rc4-next-20190412 #24 Not tainted > ------------------------------------------------------ > syz-executor.5/30036 is trying to acquire lock: > 00000000dfc2e8ba (&p->lock){+.+.}, at: seq_read+0x71/0x1130 > fs/seq_file.c:161 > > but task is already holding lock: > 00000000471a7795 (sb_writers#5){.+.+}, at: file_start_write > include/linux/fs.h:2825 [inline] > 00000000471a7795 (sb_writers#5){.+.+}, at: do_sendfile+0x9b9/0xd00 > fs/read_write.c:1442 > > which lock already depends on the new lock. > > > the existing dependency chain (in reverse order) is: > > -> #3 (sb_writers#5){.+.+}: > lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211 > percpu_down_read include/linux/percpu-rwsem.h:36 [inline] > __sb_start_write+0x20b/0x360 fs/super.c:1613 > sb_start_write include/linux/fs.h:1621 [inline] > mnt_want_write+0x3f/0xc0 fs/namespace.c:358 > ovl_want_write+0x76/0xa0 fs/overlayfs/util.c:24 > ovl_create_object+0xb3/0x2c0 fs/overlayfs/dir.c:599 > ovl_create+0x28/0x30 fs/overlayfs/dir.c:630 > lookup_open+0x12e0/0x1b10 fs/namei.c:3232 > do_last fs/namei.c:3322 [inline] > path_openat+0x14ac/0x46e0 fs/namei.c:3533 > do_filp_open+0x1a1/0x280 fs/namei.c:3563 > do_sys_open+0x3fe/0x5d0 fs/open.c:1069 > ksys_open include/linux/syscalls.h:1373 [inline] > __do_sys_creat fs/open.c:1127 [inline] > __se_sys_creat fs/open.c:1125 [inline] > __x64_sys_creat+0x61/0x80 fs/open.c:1125 > do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > -> #2 (&ovl_i_mutex_dir_key[depth]){++++}: > lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211 > down_read+0x3b/0x90 kernel/locking/rwsem.c:24 > inode_lock_shared include/linux/fs.h:782 [inline] > do_last fs/namei.c:3321 [inline] > path_openat+0x1e98/0x46e0 fs/namei.c:3533 > do_filp_open+0x1a1/0x280 fs/namei.c:3563 > do_open_execat+0x137/0x690 fs/exec.c:856 > __do_execve_file.isra.0+0x178d/0x23f0 fs/exec.c:1758 > do_execveat_common fs/exec.c:1865 [inline] > do_execve fs/exec.c:1882 [inline] > __do_sys_execve fs/exec.c:1958 [inline] > __se_sys_execve fs/exec.c:1953 [inline] > __x64_sys_execve+0x8f/0xc0 fs/exec.c:1953 > do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > -> #1 (&sig->cred_guard_mutex){+.+.}: > lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211 > __mutex_lock_common kernel/locking/mutex.c:925 [inline] > __mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1072 > mutex_lock_killable_nested+0x16/0x20 kernel/locking/mutex.c:1102 > lock_trace+0x4a/0xe0 fs/proc/base.c:388 > proc_pid_syscall+0x8a/0x220 fs/proc/base.c:623 > proc_single_show+0xf6/0x170 fs/proc/base.c:744 > seq_read+0x4db/0x1130 fs/seq_file.c:229 > do_loop_readv_writev fs/read_write.c:701 [inline] > do_loop_readv_writev fs/read_write.c:688 [inline] > do_iter_read+0x4a9/0x660 fs/read_write.c:922 > vfs_readv+0xf0/0x160 fs/read_write.c:984 > kernel_readv fs/splice.c:358 [inline] > default_file_splice_read+0x475/0x890 fs/splice.c:413 > do_splice_to+0x12a/0x190 fs/splice.c:876 > splice_direct_to_actor+0x2d2/0x970 fs/splice.c:953 > do_splice_direct+0x1da/0x2a0 fs/splice.c:1062 > do_sendfile+0x597/0xd00 fs/read_write.c:1443 > __do_sys_sendfile64 fs/read_write.c:1504 [inline] > __se_sys_sendfile64 fs/read_write.c:1490 [inline] > __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1490 > do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > -> #0 (&p->lock){+.+.}: > check_prevs_add kernel/locking/lockdep.c:2333 [inline] > validate_chain kernel/locking/lockdep.c:2714 [inline] > __lock_acquire+0x239c/0x3fb0 kernel/locking/lockdep.c:3701 > lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211 > __mutex_lock_common kernel/locking/mutex.c:925 [inline] > __mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1072 > mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 > seq_read+0x71/0x1130 fs/seq_file.c:161 > proc_reg_read+0x1fe/0x2c0 fs/proc/inode.c:227 > do_loop_readv_writev fs/read_write.c:701 [inline] > do_loop_readv_writev fs/read_write.c:688 [inline] > do_iter_read+0x4a9/0x660 fs/read_write.c:922 > vfs_readv+0xf0/0x160 fs/read_write.c:984 > kernel_readv fs/splice.c:358 [inline] > default_file_splice_read+0x475/0x890 fs/splice.c:413 > do_splice_to+0x12a/0x190 fs/splice.c:876 > splice_direct_to_actor+0x2d2/0x970 fs/splice.c:953 > do_splice_direct+0x1da/0x2a0 fs/splice.c:1062 > do_sendfile+0x597/0xd00 fs/read_write.c:1443 > __do_sys_sendfile64 fs/read_write.c:1504 [inline] > __se_sys_sendfile64 fs/read_write.c:1490 [inline] > __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1490 > do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > other info that might help us debug this: > > Chain exists of: > &p->lock --> &ovl_i_mutex_dir_key[depth] --> sb_writers#5 > > Possible unsafe locking scenario: > > CPU0 CPU1 > ---- ---- > lock(sb_writers#5); > lock(&ovl_i_mutex_dir_key[depth]); > lock(sb_writers#5); > lock(&p->lock); > > *** DEADLOCK *** > > 1 lock held by syz-executor.5/30036: > #0: 00000000471a7795 (sb_writers#5){.+.+}, at: file_start_write > include/linux/fs.h:2825 [inline] > #0: 00000000471a7795 (sb_writers#5){.+.+}, at: do_sendfile+0x9b9/0xd00 > fs/read_write.c:1442 > > stack backtrace: > CPU: 1 PID: 30036 Comm: syz-executor.5 Not tainted 5.1.0-rc4-next-20190412 > #24 > 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+0x172/0x1f0 lib/dump_stack.c:113 > print_circular_bug.isra.0.cold+0x1cc/0x28f kernel/locking/lockdep.c:1571 > check_prev_add.constprop.0+0xf11/0x23c0 kernel/locking/lockdep.c:2220 > check_prevs_add kernel/locking/lockdep.c:2333 [inline] > validate_chain kernel/locking/lockdep.c:2714 [inline] > __lock_acquire+0x239c/0x3fb0 kernel/locking/lockdep.c:3701 > lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211 > __mutex_lock_common kernel/locking/mutex.c:925 [inline] > __mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1072 > mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 > seq_read+0x71/0x1130 fs/seq_file.c:161 > proc_reg_read+0x1fe/0x2c0 fs/proc/inode.c:227 > do_loop_readv_writev fs/read_write.c:701 [inline] > do_loop_readv_writev fs/read_write.c:688 [inline] > do_iter_read+0x4a9/0x660 fs/read_write.c:922 > vfs_readv+0xf0/0x160 fs/read_write.c:984 > kernel_readv fs/splice.c:358 [inline] > default_file_splice_read+0x475/0x890 fs/splice.c:413 > do_splice_to+0x12a/0x190 fs/splice.c:876 > splice_direct_to_actor+0x2d2/0x970 fs/splice.c:953 > do_splice_direct+0x1da/0x2a0 fs/splice.c:1062 > do_sendfile+0x597/0xd00 fs/read_write.c:1443 > __do_sys_sendfile64 fs/read_write.c:1504 [inline] > __se_sys_sendfile64 fs/read_write.c:1490 [inline] > __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1490 > do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x458c29 > Code: ad b8 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 b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 > RSP: 002b:00007f0f57706c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 > RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000458c29 > RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000006 > RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000020 R11: 0000000000000246 R12: 00007f0f577076d4 > R13: 00000000004c5e10 R14: 00000000004da5c8 R15: 00000000ffffffff > > > --- > 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.
