ghsa-3xrx-73h3-j99c
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
btrfs: qgroup: fix qgroup prealloc rsv leak in subvolume operations
Create subvolume, create snapshot and delete subvolume all use btrfs_subvolume_reserve_metadata() to reserve metadata for the changes done to the parent subvolume's fs tree, which cannot be mediated in the normal way via start_transaction. When quota groups (squota or qgroups) are enabled, this reserves qgroup metadata of type PREALLOC. Once the operation is associated to a transaction, we convert PREALLOC to PERTRANS, which gets cleared in bulk at the end of the transaction.
However, the error paths of these three operations were not implementing this lifecycle correctly. They unconditionally converted the PREALLOC to PERTRANS in a generic cleanup step regardless of errors or whether the operation was fully associated to a transaction or not. This resulted in error paths occasionally converting this rsv to PERTRANS without calling record_root_in_trans successfully, which meant that unless that root got recorded in the transaction by some other thread, the end of the transaction would not free that root's PERTRANS, leaking it. Ultimately, this resulted in hitting a WARN in CONFIG_BTRFS_DEBUG builds at unmount for the leaked reservation.
The fix is to ensure that every qgroup PREALLOC reservation observes the following properties:
- any failure before record_root_in_trans is called successfully results in freeing the PREALLOC reservation.
- after record_root_in_trans, we convert to PERTRANS, and now the transaction owns freeing the reservation.
This patch enforces those properties on the three operations. Without it, generic/269 with squotas enabled at mkfs time would fail in ~5-10 runs on my system. With this patch, it ran successfully 1000 times in a row.
{
"affected": [],
"aliases": [
"CVE-2024-35956"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-05-20T10:15:10Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: qgroup: fix qgroup prealloc rsv leak in subvolume operations\n\nCreate subvolume, create snapshot and delete subvolume all use\nbtrfs_subvolume_reserve_metadata() to reserve metadata for the changes\ndone to the parent subvolume\u0027s fs tree, which cannot be mediated in the\nnormal way via start_transaction. When quota groups (squota or qgroups)\nare enabled, this reserves qgroup metadata of type PREALLOC. Once the\noperation is associated to a transaction, we convert PREALLOC to\nPERTRANS, which gets cleared in bulk at the end of the transaction.\n\nHowever, the error paths of these three operations were not implementing\nthis lifecycle correctly. They unconditionally converted the PREALLOC to\nPERTRANS in a generic cleanup step regardless of errors or whether the\noperation was fully associated to a transaction or not. This resulted in\nerror paths occasionally converting this rsv to PERTRANS without calling\nrecord_root_in_trans successfully, which meant that unless that root got\nrecorded in the transaction by some other thread, the end of the\ntransaction would not free that root\u0027s PERTRANS, leaking it. Ultimately,\nthis resulted in hitting a WARN in CONFIG_BTRFS_DEBUG builds at unmount\nfor the leaked reservation.\n\nThe fix is to ensure that every qgroup PREALLOC reservation observes the\nfollowing properties:\n\n1. any failure before record_root_in_trans is called successfully\n results in freeing the PREALLOC reservation.\n2. after record_root_in_trans, we convert to PERTRANS, and now the\n transaction owns freeing the reservation.\n\nThis patch enforces those properties on the three operations. Without\nit, generic/269 with squotas enabled at mkfs time would fail in ~5-10\nruns on my system. With this patch, it ran successfully 1000 times in a\nrow.",
"id": "GHSA-3xrx-73h3-j99c",
"modified": "2024-05-20T12:30:28Z",
"published": "2024-05-20T12:30:28Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-35956"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/14431815a4ae4bcd7c7a68b6a64c66c7712d27c9"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6c95336f5d8eb9ab79cd7306d71b6d0477363f8c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/74e97958121aa1f5854da6effba70143f051b0cd"
}
],
"schema_version": "1.4.0",
"severity": []
}
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.