CVE-2024-35956
Vulnérabilité non évaluée dans Linux (Linux)
Description
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: 1. any failure before record_root_in_trans is called successfully results in freeing the PREALLOC reservation. 2. 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.
Gravité et risque d'exploitation
CVE-2024-35956 obtient un score CVSS de 0.0/10, soit une gravité non évaluée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.23 %, ce qui la place devant 12.8 % des CVE référencées.
Que faire ?
- Vérifiez si Linux (versions 5.10, <=6.1.*, 6.9, e85fde5162bf1b242cbd6daf7dba0f9b457d592b, <=*, <945559be6e282a812dc48f7bcd5adc60901ea4a0, 2978cb474745b2d93c263008d265e89985706094, <5.10, 5.9.5, <14431815a4ae4bcd7c7a68b6a64c66c7712d27c9, 6.6.28, <=6.6.*, <=6.8.*, 0, 6.1.120, 6.8.7, <74e97958121aa1f5854da6effba70143f051b0cd, <6c95336f5d8eb9ab79cd7306d71b6d0477363f8c) est présent sur votre parc.
- Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
- À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
- Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.