Skip to content
Fencer Vulns
high 7.8

CVE-2022-48733 json

btrfs: fix use-after-free after failure to create a snapshot

published 2024-06-20 2 y ago modified 2026-08-05 3 mo ago also EUVD-2022-53612

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 13%
public exploits
0
none known

Summary

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

btrfs: fix use-after-free after failure to create a snapshot

At ioctl.c:create_snapshot(), we allocate a pending snapshot structure and then attach it to the transaction's list of pending snapshots. After that we call btrfs_commit_transaction(), and if that returns an error we jump to 'fail' label, where we kfree() the pending snapshot structure. This can result in a later use-after-free of the pending snapshot:

1) We allocated the pending snapshot and added it to the transaction's list of pending snapshots;

2) We call btrfs_commit_transaction(), and it fails either at the first call to btrfs_run_delayed_refs() or btrfs_start_dirty_block_groups(). In both cases, we don't abort the transaction and we release our transaction handle. We jump to the 'fail' label and free the pending snapshot structure. We return with the pending snapshot still in the transaction's list;

3) Another task commits the transaction. This time there's no error at all, and then during the transaction commit it accesses a pointer to the pending snapshot structure that the snapshot creation task has already freed, resulting in a user-after-free.

This issue could actually be detected by smatch, which produced the following warning:

fs/btrfs/ioctl.c:843 create_snapshot() warn: '&pending_snapshot->list' not removed from list

So fix this by not having the snapshot creation ioctl directly add the pending snapshot to the transaction's list. Instead add the pending snapshot to the transaction handle, and then at btrfs_commit_transaction() we add the snapshot to the list only when we can guarantee that any error returned after that point will result in a transaction abort, in which case the ioctl code can safely free the pending snapshot and no one can access it anymore.

Patch / fix

  • Linux Linux 5.10.226, 5.15.22, 5.16.8, 5.17
  • linux Debian 14, Debian 13, Debian 12 5.16.10-1

debian advisories DEBIAN-CVE-2022-48733

  • linux Ubuntu 20.04 LTS 5.4.0-202.222
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1136.146
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1140.149
  • linux-ibm Ubuntu 20.04 LTS 5.4.0-1083.88
  • linux-iot Ubuntu 20.04 LTS 5.4.0-1045.46
  • linux-kvm Ubuntu 20.04 LTS 5.4.0-1124.132
  • linux-azure Ubuntu 20.04 LTS 5.4.0-1142.149
  • linux-raspi Ubuntu 20.04 LTS 5.4.0-1120.132

ubuntu advisories UBUNTU-CVE-2022-48733

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • dtb-aarch64 openSUSE Leap 15.5 5.14.21-150500.55.73.1
  • kernel-64kb SLE Module for Basesystem 15 SP5, openSUSE Leap 15.5 5.14.21-150500.55.73.1
  • kernel-syms SLE Module for Development Tools 15 SP5, openSUSE Leap 15.5 5.14.21-150500.55.73.1
  • kernel-obs-qa openSUSE Leap 15.5 5.14.21-150500.55.73.1
  • kernel-source SLE Module for Development Tools 15 SP5, SLE Module for Basesystem 15 SP5, openSUSE Leap 15.5 5.14.21-150500.55.73.1
  • kernel-default SLE Workstation Extension 15 SP5, SLE Module for Legacy 15 SP5, SLE Module for Basesystem 15 SP5 +5 more 5.14.21-150500.55.73.1
  • kernel-kvmsmall openSUSE Leap 15.5 5.14.21-150500.55.73.1
  • kernel-zfcpdump SLE Module for Basesystem 15 SP5, openSUSE Leap 15.5 5.14.21-150500.55.73.1

suse advisories SUSE-SU-2024:2939-1SUSE-SU-2024:2561-1SUSE-SU-2024:2394-1SUSE-SU-2024:2381-1SUSE-SU-2024:2372-1SUSE-SU-2024:2360-1

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-2022-48733 updated cvss 7.8

kernel: btrfs: fix use-after-free after failure to create a snapshot

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more 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
    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

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

0.23% chance of exploitation in the next 30 days, higher than 13% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Weakness
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.