On Tue, 07 May 2024 22:36:18 -0700 > syzbot has found a reproducer for the following issue on: > > HEAD commit: dccb07f2914c Merge tag 'for-6.9-rc7-tag' of git://git.kern.. > git tree: upstream > console+strace: https://syzkaller.appspot.com/x/log.txt?x=137daa6c980000 > kernel config: https://syzkaller.appspot.com/x/.config?x=9d7ea7de0cb32587 > dashboard link: https://syzkaller.appspot.com/bug?extid=4c493dcd5a68168a94b2 > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1134f3c0980000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1367a504980000 > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/ea1961ce01fe/disk-dccb07f2.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/445a00347402/vmlinux-dccb07f2.xz > kernel image: https://storage.googleapis.com/syzbot-assets/461aed7c4df3/bzImage-dccb07f2.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+4c493dcd5a68168a94b2@xxxxxxxxxxxxxxxxxxxxxxxxx > > ====================================================== > WARNING: possible circular locking dependency detected > 6.9.0-rc7-syzkaller-00012-gdccb07f2914c #0 Not tainted > ------------------------------------------------------ > syz-executor149/5078 is trying to acquire lock: > ffff88802a978888 (&of->mutex){+.+.}-{3:3}, at: kernfs_seq_start+0x53/0x3b0 fs/kernfs/file.c:154 > > but task is already holding lock: > ffff88802d80b540 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0xb7/0xd60 fs/seq_file.c:182 > > which lock already depends on the new lock. > > > the existing dependency chain (in reverse order) is: > > -> #4 (&p->lock){+.+.}-{3:3}: > lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754 > __mutex_lock_common kernel/locking/mutex.c:608 [inline] > __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752 > seq_read_iter+0xb7/0xd60 fs/seq_file.c:182 > call_read_iter include/linux/fs.h:2104 [inline] > copy_splice_read+0x662/0xb60 fs/splice.c:365 > do_splice_read fs/splice.c:985 [inline] > splice_file_to_pipe+0x299/0x500 fs/splice.c:1295 > do_sendfile+0x515/0xdc0 fs/read_write.c:1301 > __do_sys_sendfile64 fs/read_write.c:1362 [inline] > __se_sys_sendfile64+0x17c/0x1e0 fs/read_write.c:1348 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > -> #3 (&pipe->mutex){+.+.}-{3:3}: > lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754 > __mutex_lock_common kernel/locking/mutex.c:608 [inline] > __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752 > iter_file_splice_write+0x335/0x14e0 fs/splice.c:687 > backing_file_splice_write+0x2bc/0x4c0 fs/backing-file.c:289 > ovl_splice_write+0x3cf/0x500 fs/overlayfs/file.c:379 > do_splice_from fs/splice.c:941 [inline] > do_splice+0xd77/0x1880 fs/splice.c:1354 > __do_splice fs/splice.c:1436 [inline] > __do_sys_splice fs/splice.c:1652 [inline] > __se_sys_splice+0x331/0x4a0 fs/splice.c:1634 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > -> #2 (sb_writers#4){.+.+}-{0:0}: > lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754 > percpu_down_read include/linux/percpu-rwsem.h:51 [inline] > __sb_start_write include/linux/fs.h:1664 [inline] > sb_start_write+0x4d/0x1c0 include/linux/fs.h:1800 > mnt_want_write+0x3f/0x90 fs/namespace.c:409 > ovl_create_object+0x13b/0x370 fs/overlayfs/dir.c:629 > lookup_open fs/namei.c:3497 [inline] > open_last_lookups fs/namei.c:3566 [inline] > path_openat+0x1425/0x3240 fs/namei.c:3796 > do_filp_open+0x235/0x490 fs/namei.c:3826 > do_sys_openat2+0x13e/0x1d0 fs/open.c:1406 > do_sys_open fs/open.c:1421 [inline] > __do_sys_open fs/open.c:1429 [inline] > __se_sys_open fs/open.c:1425 [inline] > __x64_sys_open+0x225/0x270 fs/open.c:1425 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > -> #1 (&ovl_i_mutex_dir_key[depth]){++++}-{3:3}: > lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754 > down_read+0xb1/0xa40 kernel/locking/rwsem.c:1526 > inode_lock_shared include/linux/fs.h:805 [inline] > lookup_slow+0x45/0x70 fs/namei.c:1708 > walk_component+0x2e1/0x410 fs/namei.c:2004 > lookup_last fs/namei.c:2461 [inline] > path_lookupat+0x16f/0x450 fs/namei.c:2485 > filename_lookup+0x256/0x610 fs/namei.c:2514 > kern_path+0x35/0x50 fs/namei.c:2622 > lookup_bdev+0xc5/0x290 block/bdev.c:1136 > resume_store+0x1a0/0x710 kernel/power/hibernate.c:1235 > kernfs_fop_write_iter+0x3a1/0x500 fs/kernfs/file.c:334 > call_write_iter include/linux/fs.h:2110 [inline] > new_sync_write fs/read_write.c:497 [inline] > vfs_write+0xa84/0xcb0 fs/read_write.c:590 > ksys_write+0x1a0/0x2c0 fs/read_write.c:643 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > -> #0 (&of->mutex){+.+.}-{3:3}: > check_prev_add kernel/locking/lockdep.c:3134 [inline] > check_prevs_add kernel/locking/lockdep.c:3253 [inline] > validate_chain+0x18cb/0x58e0 kernel/locking/lockdep.c:3869 > __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137 > lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754 > __mutex_lock_common kernel/locking/mutex.c:608 [inline] > __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752 > kernfs_seq_start+0x53/0x3b0 fs/kernfs/file.c:154 > traverse+0x14f/0x550 fs/seq_file.c:106 > seq_read_iter+0xc5e/0xd60 fs/seq_file.c:195 > call_read_iter include/linux/fs.h:2104 [inline] > copy_splice_read+0x662/0xb60 fs/splice.c:365 > do_splice_read fs/splice.c:985 [inline] > splice_file_to_pipe+0x299/0x500 fs/splice.c:1295 > do_sendfile+0x515/0xdc0 fs/read_write.c:1301 > __do_sys_sendfile64 fs/read_write.c:1362 [inline] > __se_sys_sendfile64+0x17c/0x1e0 fs/read_write.c:1348 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > other info that might help us debug this: > > Chain exists of: > &of->mutex --> &pipe->mutex --> &p->lock > > Possible unsafe locking scenario: > > CPU0 CPU1 > ---- ---- > lock(&p->lock); > lock(&pipe->mutex); > lock(&p->lock); > lock(&of->mutex); > > *** DEADLOCK *** This shows 16b52bbee482 ("kernfs: annotate different lockdep class for of->mutex of writable files") is a bandaid. > > 2 locks held by syz-executor149/5078: > #0: ffff88807de89868 (&pipe->mutex){+.+.}-{3:3}, at: splice_file_to_pipe+0x2e/0x500 fs/splice.c:1292 > #1: ffff88802d80b540 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0xb7/0xd60 fs/seq_file.c:182 > > stack backtrace: > CPU: 0 PID: 5078 Comm: syz-executor149 Not tainted 6.9.0-rc7-syzkaller-00012-gdccb07f2914c #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024 > Call Trace: > <TASK> > __dump_stack lib/dump_stack.c:88 [inline] > dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114 > check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2187 > check_prev_add kernel/locking/lockdep.c:3134 [inline] > check_prevs_add kernel/locking/lockdep.c:3253 [inline] > validate_chain+0x18cb/0x58e0 kernel/locking/lockdep.c:3869 > __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137 > lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754 > __mutex_lock_common kernel/locking/mutex.c:608 [inline] > __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752 > kernfs_seq_start+0x53/0x3b0 fs/kernfs/file.c:154 > traverse+0x14f/0x550 fs/seq_file.c:106 > seq_read_iter+0xc5e/0xd60 fs/seq_file.c:195 > call_read_iter include/linux/fs.h:2104 [inline] > copy_splice_read+0x662/0xb60 fs/splice.c:365 > do_splice_read fs/splice.c:985 [inline] > splice_file_to_pipe+0x299/0x500 fs/splice.c:1295 > do_sendfile+0x515/0xdc0 fs/read_write.c:1301 > __do_sys_sendfile64 fs/read_write.c:1362 [inline] > __se_sys_sendfile64+0x17c/0x1e0 fs/read_write.c:1348 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > RIP: 0033:0x7f7d8d33f8e9 > Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 18 00 00 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 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48 > RSP: 002b:00007f7d8d2b8218 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 > RAX: ffffffffffffffda RBX: 00007f7d8d3c9428 RCX: 00007f7d8d33f8e9 > RDX: 0000000000000000 RSI: 0000000000000007 RDI: 0000000000000006 > RBP: 00007f7d8d3c9420 R08: 00007ffdc82d7c57 R09: 0000000000000000 > R10: 0000000000000004 R11: 0000000000000246 R12: 00007f7d8d39606c > R13: 0030656c69662f2e R14: 0079616c7265766f R15: 00007f7d8d39603b > </TASK> > > > --- > If you want syzbot to run the reproducer, reply with: > #syz test: git://repo/address.git branch-or-commit-hash > If you attach or paste a git patch, syzbot will apply it before testing. >
