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Fencer Vulns
no cvss —

CVE-2023-54023 json

btrfs: fix race between balance and cancel/pause

published 2025-12-24 10 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-205131

cvss
—
not scored
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 8%
public exploits
0
none known

Summary

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

btrfs: fix race between balance and cancel/pause

Syzbot reported a panic that looks like this:

assertion failed: fs_info->exclusive_operation == BTRFS_EXCLOP_BALANCE_PAUSED, in fs/btrfs/ioctl.c:465 ------------[ cut here ]------------ kernel BUG at fs/btrfs/messages.c:259! RIP: 0010:btrfs_assertfail+0x2c/0x30 fs/btrfs/messages.c:259 Call Trace: <TASK> btrfs_exclop_balance fs/btrfs/ioctl.c:465 [inline] btrfs_ioctl_balance fs/btrfs/ioctl.c:3564 [inline] btrfs_ioctl+0x531e/0x5b30 fs/btrfs/ioctl.c:4632 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __x64_sys_ioctl+0x197/0x210 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd

The reproducer is running a balance and a cancel or pause in parallel. The way balance finishes is a bit wonky, if we were paused we need to save the balance_ctl in the fs_info, but clear it otherwise and cleanup. However we rely on the return values being specific errors, or having a cancel request or no pause request. If balance completes and returns 0, but we have a pause or cancel request we won't do the appropriate cleanup, and then the next time we try to start a balance we'll trip this ASSERT.

The error handling is just wrong here, we always want to clean up, unless we got -ECANCELLED and we set the appropriate pause flag in the exclusive op. With this patch the reproducer ran for an hour without tripping, previously it would trip in less than a few minutes.

Patch / fix

  • Linux Linux 6.1.42, 6.4.7, 6.5
  • linux Debian 12 6.1.52-1
  • linux Debian 14, Debian 13 6.4.11-1

debian advisories DEBIAN-CVE-2023-54023

  • kernel-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-40.1
  • kernel-source-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-40.1
  • kernel-source Linux Micro 6.1, Linux Micro 6.0 6.4.0-39.1
  • kernel-default Linux Micro 6.1, Linux Micro 6.0 6.4.0-39.1
  • kernel-kvmsmall Linux Micro 6.1, Linux Micro 6.0 6.4.0-39.1
  • kernel-default-base Linux Micro 6.1, Linux Micro 6.0 6.4.0-39.1.21.16
  • kernel-64kb SLE Module for Basesystem 15 SP7 6.4.0-150700.53.28.1
  • kernel-syms SLE Module for Development Tools 15 SP7 6.4.0-150700.53.28.1

suse advisories SUSE-SU-2026:20845-1SUSE-SU-2026:20876-1SUSE-SU-2026:20477-1SUSE-SU-2026:20498-1SUSE-SU-2026:0315-1SUSE-SU-2026:0293-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2023-54023 updated cvss 5.5

kernel: btrfs: fix race between balance and cancel/pause

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more
    affected: no fix available “Fix deferred”
  • Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.18% chance of exploitation in the next 30 days, higher than 8% of all scored CVEs (FIRST EPSS, 2026-11-08).

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.