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.
Metrics
Affected Vendors & Products
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
Tue, 27 May 2025 19:00:00 +0000
Type | Values Removed | Values Added |
---|---|---|
CPEs | cpe:2.3:o:linux:linux_kernel:5.17:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.17:rc2:*:*:*:*:*:* |
Tue, 05 Nov 2024 08:15:00 +0000
Type | Values Removed | Values Added |
---|---|---|
Metrics |
ssvc
|
Thu, 12 Sep 2024 12:30:00 +0000
Type | Values Removed | Values Added |
---|---|---|
Metrics |
ssvc
|
Thu, 12 Sep 2024 12:00:00 +0000
Type | Values Removed | Values Added |
---|---|---|
References |
|
Wed, 11 Sep 2024 13:30:00 +0000
Type | Values Removed | Values Added |
---|---|---|
Metrics |
ssvc
|
Mon, 19 Aug 2024 18:00:00 +0000
Type | Values Removed | Values Added |
---|---|---|
First Time appeared |
Linux
Linux linux Kernel |
|
CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
Vendors & Products |
Linux
Linux linux Kernel |
|
Metrics |
cvssV3_1
|
cvssV3_1
|

Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2025-05-04T08:22:03.198Z
Reserved: 2024-06-20T11:09:39.053Z
Link: CVE-2022-48733

Updated: 2024-08-03T15:25:01.133Z

Status : Analyzed
Published: 2024-06-20T12:15:11.700
Modified: 2025-05-27T18:31:52.007
Link: CVE-2022-48733


No data.