In the Linux kernel, the following vulnerability has been resolved:

btrfs: fix the inode leak in btrfs_iget()

[BUG]
There is a bug report that a syzbot reproducer can lead to the following
busy inode at unmount time:

BTRFS info (device loop1): last unmount of filesystem 1680000e-3c1e-4c46-84b6-56bd3909af50
VFS: Busy inodes after unmount of loop1 (btrfs)
------------[ cut here ]------------
kernel BUG at fs/super.c:650!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 48168 Comm: syz-executor Not tainted 6.15.0-rc2-00471-g119009db2674 #2 PREEMPT(full)
Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:generic_shutdown_super+0x2e9/0x390 fs/super.c:650
Call Trace:
<TASK>
kill_anon_super+0x3a/0x60 fs/super.c:1237
btrfs_kill_super+0x3b/0x50 fs/btrfs/super.c:2099
deactivate_locked_super+0xbe/0x1a0 fs/super.c:473
deactivate_super fs/super.c:506 [inline]
deactivate_super+0xe2/0x100 fs/super.c:502
cleanup_mnt+0x21f/0x440 fs/namespace.c:1435
task_work_run+0x14d/0x240 kernel/task_work.c:227
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:329 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0x269/0x290 kernel/entry/common.c:218
do_syscall_64+0xd4/0x250 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
</TASK>

[CAUSE]
When btrfs_alloc_path() failed, btrfs_iget() directly returned without
releasing the inode already allocated by btrfs_iget_locked().

This results the above busy inode and trigger the kernel BUG.

[FIX]
Fix it by calling iget_failed() if btrfs_alloc_path() failed.

If we hit error inside btrfs_read_locked_inode(), it will properly call
iget_failed(), so nothing to worry about.

Although the iget_failed() cleanup inside btrfs_read_locked_inode() is a
break of the normal error handling scheme, let's fix the obvious bug
and backport first, then rework the error handling later.
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Wed, 21 May 2025 03:00:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Low


Tue, 20 May 2025 15:30:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: btrfs: fix the inode leak in btrfs_iget() [BUG] There is a bug report that a syzbot reproducer can lead to the following busy inode at unmount time: BTRFS info (device loop1): last unmount of filesystem 1680000e-3c1e-4c46-84b6-56bd3909af50 VFS: Busy inodes after unmount of loop1 (btrfs) ------------[ cut here ]------------ kernel BUG at fs/super.c:650! Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI CPU: 0 UID: 0 PID: 48168 Comm: syz-executor Not tainted 6.15.0-rc2-00471-g119009db2674 #2 PREEMPT(full) Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:generic_shutdown_super+0x2e9/0x390 fs/super.c:650 Call Trace: <TASK> kill_anon_super+0x3a/0x60 fs/super.c:1237 btrfs_kill_super+0x3b/0x50 fs/btrfs/super.c:2099 deactivate_locked_super+0xbe/0x1a0 fs/super.c:473 deactivate_super fs/super.c:506 [inline] deactivate_super+0xe2/0x100 fs/super.c:502 cleanup_mnt+0x21f/0x440 fs/namespace.c:1435 task_work_run+0x14d/0x240 kernel/task_work.c:227 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:329 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0x269/0x290 kernel/entry/common.c:218 do_syscall_64+0xd4/0x250 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f </TASK> [CAUSE] When btrfs_alloc_path() failed, btrfs_iget() directly returned without releasing the inode already allocated by btrfs_iget_locked(). This results the above busy inode and trigger the kernel BUG. [FIX] Fix it by calling iget_failed() if btrfs_alloc_path() failed. If we hit error inside btrfs_read_locked_inode(), it will properly call iget_failed(), so nothing to worry about. Although the iget_failed() cleanup inside btrfs_read_locked_inode() is a break of the normal error handling scheme, let's fix the obvious bug and backport first, then rework the error handling later.
Title btrfs: fix the inode leak in btrfs_iget()
References

cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2025-05-26T05:23:23.604Z

Reserved: 2025-04-16T04:51:23.965Z

Link: CVE-2025-37904

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Awaiting Analysis

Published: 2025-05-20T16:15:26.820

Modified: 2025-05-21T20:25:16.407

Link: CVE-2025-37904

cve-icon Redhat

Severity : Low

Publid Date: 2025-05-20T00:00:00Z

Links: CVE-2025-37904 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2025-06-27T09:26:51Z