Messages in this thread |  | | From | Mateusz Guzik <> | | Date | Thu, 4 Dec 2025 08:45:08 +0100 | | Subject | Re: [syzbot] [exfat?] [ocfs2?] kernel BUG in link_path_walk |
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On Thu, Dec 4, 2025 at 2:21 AM syzbot <syzbot+d222f4b7129379c3d5bc@syzkaller.appspotmail.com> wrote: > > Hello, > > syzbot has tested the proposed patch but the reproducer is still triggering an issue: > kernel BUG in link_path_walk > > (syz.0.73,6964,1):ocfs2_find_entry_id:420 ERROR: status = -30 > ------------[ cut here ]------------ > kernel BUG at fs/namei.c:2532!
On the commit syzbot is testing on (b2c27842) and with the patch, the triggered assert is the second one on S_ISDIR: VFS_BUG_ON(!d_can_lookup(nd->path.dentry)); VFS_BUG_ON(!S_ISDIR(nd->path.dentry->d_inode->i_mode));
d_can_lookup is __d_entry_type(dentry) == DCACHE_DIRECTORY_TYPE;
Or to put it differently, lookup got entered with a bogus state of a dentry claiming it is a directory, with an inode which is not. Per the i_mode reported in the opening mail it is a regular file instead.
While I don't see how this can happen, I don't think it is *my* bug either -- merely nothing else asserted on the 2 things being in tandem.
syzbot likes to operate on corrupted filesystems, so I'm going to assume things are going haywire in ocfs2 until proven otherwise.
> Oops: invalid opcode: 0000 [#1] SMP KASAN PTI > CPU: 1 UID: 0 PID: 6964 Comm: syz.0.73 Not tainted syzkaller #0 PREEMPT(full) > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 > RIP: 0010:link_path_walk+0x1a57/0x1a90 fs/namei.c:2532 > Code: 89 e9 80 e1 07 fe c1 38 c1 0f 8c be fd ff ff 4c 89 ef e8 2c e5 e9 ff e9 b1 fd ff ff e8 62 90 83 ff 90 0f 0b e8 5a 90 83 ff 90 <0f> 0b e8 52 90 83 ff 90 0f 0b e8 4a 90 83 ff 4c 89 ff 48 c7 c6 40 > RSP: 0018:ffffc9000491f8a0 EFLAGS: 00010293 > RAX: ffffffff823e22d6 RBX: dffffc0000000000 RCX: ffff8880250f3d00 > RDX: 0000000000000000 RSI: 0000000000008000 RDI: 0000000000004000 > RBP: ffff888079181120 R08: ffff8880299ef520 R09: ffff88807acd2000 > R10: ffff8880299ef520 R11: ffff88807acd2000 R12: ffffc9000491fc58 > R13: ffffc9000491fc28 R14: 0000000000008000 R15: 0000000000100000 > FS: 00007ff92e2e36c0(0000) GS:ffff888125f49000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000555575344808 CR3: 0000000025c92000 CR4: 00000000003526f0 > Call Trace: > <TASK> > path_openat+0x2b3/0x3dd0 fs/namei.c:4787 > do_filp_open+0x1fa/0x410 fs/namei.c:4818 > do_sys_openat2+0x121/0x200 fs/open.c:1430 > do_sys_open fs/open.c:1436 [inline] > __do_sys_open fs/open.c:1444 [inline] > __se_sys_open fs/open.c:1440 [inline] > __x64_sys_open+0x11e/0x150 fs/open.c:1440 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > RIP: 0033:0x7ff92d38f749 > Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48 > RSP: 002b:00007ff92e2e3038 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 > RAX: ffffffffffffffda RBX: 00007ff92d5e5fa0 RCX: 00007ff92d38f749 > RDX: 0000000000000000 RSI: 0000000000145142 RDI: 0000200000000240 > RBP: 00007ff92d413f91 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 > R13: 00007ff92d5e6038 R14: 00007ff92d5e5fa0 R15: 00007ffda4bd0278 > </TASK> > Modules linked in: > ---[ end trace 0000000000000000 ]--- > RIP: 0010:link_path_walk+0x1a57/0x1a90 fs/namei.c:2532 > Code: 89 e9 80 e1 07 fe c1 38 c1 0f 8c be fd ff ff 4c 89 ef e8 2c e5 e9 ff e9 b1 fd ff ff e8 62 90 83 ff 90 0f 0b e8 5a 90 83 ff 90 <0f> 0b e8 52 90 83 ff 90 0f 0b e8 4a 90 83 ff 4c 89 ff 48 c7 c6 40 > RSP: 0018:ffffc9000491f8a0 EFLAGS: 00010293 > RAX: ffffffff823e22d6 RBX: dffffc0000000000 RCX: ffff8880250f3d00 > RDX: 0000000000000000 RSI: 0000000000008000 RDI: 0000000000004000 > RBP: ffff888079181120 R08: ffff8880299ef520 R09: ffff88807acd2000 > R10: ffff8880299ef520 R11: ffff88807acd2000 R12: ffffc9000491fc58 > R13: ffffc9000491fc28 R14: 0000000000008000 R15: 0000000000100000 > FS: 00007ff92e2e36c0(0000) GS:ffff888125e49000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007f1310116e9c CR3: 0000000025c92000 CR4: 00000000003526f0 > > > Tested on: > > commit: b2c27842 Add linux-next specific files for 20251203 > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=15d7801a580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=caadf525b0ab8d17 > dashboard link: https://syzkaller.appspot.com/bug?extid=d222f4b7129379c3d5bc > compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8 > patch: https://syzkaller.appspot.com/x/patch.diff?x=1281d4c2580000 >
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