ghsa-grhv-62hf-9jg3
Vulnerability from github
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.
{
"affected": [],
"aliases": [
"CVE-2022-48733"
],
"database_specific": {
"cwe_ids": [
"CWE-416"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-06-20T12:15:11Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: fix use-after-free after failure to create a snapshot\n\nAt ioctl.c:create_snapshot(), we allocate a pending snapshot structure and\nthen attach it to the transaction\u0027s list of pending snapshots. After that\nwe call btrfs_commit_transaction(), and if that returns an error we jump\nto \u0027fail\u0027 label, where we kfree() the pending snapshot structure. This can\nresult in a later use-after-free of the pending snapshot:\n\n1) We allocated the pending snapshot and added it to the transaction\u0027s\n list of pending snapshots;\n\n2) We call btrfs_commit_transaction(), and it fails either at the first\n call to btrfs_run_delayed_refs() or btrfs_start_dirty_block_groups().\n In both cases, we don\u0027t abort the transaction and we release our\n transaction handle. We jump to the \u0027fail\u0027 label and free the pending\n snapshot structure. We return with the pending snapshot still in the\n transaction\u0027s list;\n\n3) Another task commits the transaction. This time there\u0027s no error at\n all, and then during the transaction commit it accesses a pointer\n to the pending snapshot structure that the snapshot creation task\n has already freed, resulting in a user-after-free.\n\nThis issue could actually be detected by smatch, which produced the\nfollowing warning:\n\n fs/btrfs/ioctl.c:843 create_snapshot() warn: \u0027\u0026pending_snapshot-\u003elist\u0027 not removed from list\n\nSo fix this by not having the snapshot creation ioctl directly add the\npending snapshot to the transaction\u0027s list. Instead add the pending\nsnapshot to the transaction handle, and then at btrfs_commit_transaction()\nwe add the snapshot to the list only when we can guarantee that any error\nreturned after that point will result in a transaction abort, in which\ncase the ioctl code can safely free the pending snapshot and no one can\naccess it anymore.",
"id": "GHSA-grhv-62hf-9jg3",
"modified": "2024-09-12T12:30:27Z",
"published": "2024-06-20T12:31:21Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-48733"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/28b21c558a3753171097193b6f6602a94169093a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7e4c72dbaf62f8978af8321a24dbd35566d3a78a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9372fa1d73da5f1673921e365d0cd2c27ec7adc2"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a7b717fa15165d3d9245614680bebc48a52ac05d"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
Sightings
| Author | Source | Type | Date |
|---|
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