Re: [syzbot] [ocfs2?] VFS: Busy inodes after unmount (use-after-free)

Re: [syzbot] [ocfs2?] VFS: Busy inodes after unmount (use-after-free)

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
VFS: Busy inodes after unmount (use-after-free)

ocfs2: Unmounting device (7,0) on (node local)
VFS: Busy inodes after unmount of loop0 (ocfs2)
------------[ cut here ]------------
kernel BUG at fs/super.c:652!
Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 0 UID: 0 PID: 6441 Comm: syz-executor Not tainted 6.12.0-rc6-syzkaller-g59b723cd2adb #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
RIP: 0010:generic_shutdown_super+0x2ca/0x2d0 fs/super.c:650
Code: 1b 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 f9 23 ed ff 48 8b 13 48 c7 c7 80 be 18 8c 4c 89 e6 e8 87 3f ad 09 90 <0f> 0b 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc9000354fd20 EFLAGS: 00010246
RAX: 000000000000002f RBX: ffffffff8ee531e0 RCX: e6b6b127fe74ba00
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: 1ffff1100f467cf0 R08: ffffffff8174a12c R09: fffffbfff1cf9fd0
R10: dffffc0000000000 R11: fffffbfff1cf9fd0 R12: ffff88807a33e668
R13: dffffc0000000000 R14: ffffffff8c49f718 R15: ffff88807a33e780
FS:  0000555593ff6500(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c00221c000 CR3: 0000000060ea2000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 kill_block_super+0x44/0x90 fs/super.c:1710
 deactivate_locked_super+0xc4/0x130 fs/super.c:473
 cleanup_mnt+0x41f/0x4b0 fs/namespace.c:1373
 task_work_run+0x24f/0x310 kernel/task_work.c:239
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x168/0x370 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8ed837fa47
Code: a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 a8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffcdc5c5528 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f8ed837fa47
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffcdc5c55e0
RBP: 00007ffcdc5c55e0 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffcdc5c6660
R13: 00007f8ed83f11cc R14: 000000000001b0d9 R15: 00007ffcdc5c66a0
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:generic_shutdown_super+0x2ca/0x2d0 fs/super.c:650
Code: 1b 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 f9 23 ed ff 48 8b 13 48 c7 c7 80 be 18 8c 4c 89 e6 e8 87 3f ad 09 90 <0f> 0b 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc9000354fd20 EFLAGS: 00010246
RAX: 000000000000002f RBX: ffffffff8ee531e0 RCX: e6b6b127fe74ba00
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: 1ffff1100f467cf0 R08: ffffffff8174a12c R09: fffffbfff1cf9fd0
R10: dffffc0000000000 R11: fffffbfff1cf9fd0 R12: ffff88807a33e668
R13: dffffc0000000000 R14: ffffffff8c49f718 R15: ffff88807a33e780
FS:  0000555593ff6500(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000563a27431950 CR3: 0000000060ea2000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


Tested on:

commit:         59b723cd Linux 6.12-rc6
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10202d5f980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=dc23b43a0f2f7cf7
dashboard link: https://syzkaller.appspot.com/bug?extid=0af00f6a2cba2058b5db
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Note: no patches were applied.

Re: VFS: Busy inodes after unmount (use-after-free)

[Tetsuo Handa]

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git v6.12

 fs/ocfs2/namei.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/ocfs2/namei.c b/fs/ocfs2/namei.c
index 59c92353151a..5550f8afa438 100644
--- a/fs/ocfs2/namei.c
+++ b/fs/ocfs2/namei.c
@@ -200,8 +200,10 @@ static struct inode *ocfs2_get_init_inode(struct inode *dir, umode_t mode)
 	mode = mode_strip_sgid(&nop_mnt_idmap, dir, mode);
 	inode_init_owner(&nop_mnt_idmap, inode, dir, mode);
 	status = dquot_initialize(inode);
-	if (status)
+	if (status) {
+		iput(inode);
 		return ERR_PTR(status);
+	}
 
 	return inode;
 }
-- 
2.47.0

Re: [syzbot] [ocfs2?] VFS: Busy inodes after unmount (use-after-free)

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+0af00f6a2cba2058b5db@syzkaller.appspotmail.com
Tested-by: syzbot+0af00f6a2cba2058b5db@syzkaller.appspotmail.com

Tested on:

commit:         adc21867 Linux 6.12
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git v6.12
console output: https://syzkaller.appspot.com/x/log.txt?x=14bf36e8580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8dfe7071ced70e76
dashboard link: https://syzkaller.appspot.com/bug?extid=0af00f6a2cba2058b5db
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=12c281c0580000

Note: testing is done by a robot and is best-effort only.