CVE-2023-53339: btrfs: fix BUG_ON condition in btrfs_cancel_balance

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-09-17 · updated 2026-06-17
Weakness: CWE-617

Description

In the Linux kernel, the following vulnerability has been resolved: btrfs: fix BUG_ON condition in btrfs_cancel_balance Pausing and canceling balance can race to interrupt balance lead to BUG_ON panic in btrfs_cancel_balance. The BUG_ON condition in btrfs_cancel_balance does not take this race scenario into account. However, the race condition has no other side effects. We can fix that. Reproducing it with panic trace like this: kernel BUG at fs/btrfs/volumes.c:4618! RIP: 0010:btrfs_cancel_balance+0x5cf/0x6a0 Call Trace: <TASK> ? do_nanosleep+0x60/0x120 ? hrtimer_nanosleep+0xb7/0x1a0 ? sched_core_clone_cookie+0x70/0x70 btrfs_ioctl_balance_ctl+0x55/0x70 btrfs_ioctl+0xa46/0xd20 __x64_sys_ioctl+0x7d/0xa0 do_syscall_64+0x38/0x80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Race scenario as follows: > mutex_unlock(&fs_info->balance_mutex); > -------------------- > .......issue pause and cancel req in another thread > -------------------- > ret = __btrfs_balance(fs_info); > > mutex_lock(&fs_info->balance_mutex); > if (ret == -ECANCELED && atomic_read(&fs_info->balance_pause_req)) { > btrfs_info(fs_info, "balance: paused"); > btrfs_exclop_balance(fs_info, BTRFS_EXCLOP_BALANCE_PAUSED); > }

Affected products

Linux kernel: before 4.19.293; from 4.20 before 5.4.255; from 5.5 before 5.10.192; from 5.11 before 5.15.128; from 5.16 before 6.1.47; from 6.2 before 6.4.12 — fixed in 4.19.293, 5.10.192, 5.15.128, 5.4.255, 6.1.47, 6.4.12

How to fix

Upgrade to a fixed version: Linux kernel 4.19.293, 5.10.192, 5.15.128, 5.4.255. Check the vendor advisory for mitigations.

References

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