CVE-2022-48733
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…
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.23%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
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.
- CVSS 3.1
- 7.8 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 0.23% probability · 14th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-416
- Affected
- linux/linux kernel
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
EPSS 0.2% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://git.kernel.org/stable/c/28b21c558a3753171097193b6f6602a94169093aPatch
- https://git.kernel.org/stable/c/7e4c72dbaf62f8978af8321a24dbd35566d3a78aPatch
- https://git.kernel.org/stable/c/9372fa1d73da5f1673921e365d0cd2c27ec7adc2Patch
- https://git.kernel.org/stable/c/a7b717fa15165d3d9245614680bebc48a52ac05dPatch
- https://git.kernel.org/stable/c/28b21c558a3753171097193b6f6602a94169093aPatch
- https://git.kernel.org/stable/c/9372fa1d73da5f1673921e365d0cd2c27ec7adc2Patch
- https://git.kernel.org/stable/c/a7b717fa15165d3d9245614680bebc48a52ac05dPatch
- https://lists.debian.org/debian-lts-announce/2024/10/msg00003.html
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.