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CVE-2022-49272

Vulnérabilité non évaluée dans Linux (Linux)

CVSS 0.0 · Non évaluée
EPSS 0.2%
Linux•Linux•Versions : <7777744e92a0b30e3e0cce2758d911837011ebd9, <7e9133607e1501c94881be35e118d8f84d96dcb4, <be9813ad2fc8f0885f5ce6925af0d993ce5da4e5, 5.17.1, <9661bf674d6a82b76e4ae424438a8ce1e3ed855d, 08d1807f097a63ea00a7067dad89c1c81cb2115e, <40f4cffbe13a51faf136faf5f9ef6847782cd595, <5.10.110, b3830197aa7413c65767cf5a1aa8775c83f0dbf7, 5.15.32, <5.15.33, 8527c8f052fb42091c6569cb928e472376a4a889, <9017201e8d8c6d1472273361389ed431188584a0, <abedf0d08c79d76da0d6fa0d5dbbc98871dcbc2e, 4d1b0ace2d56dc27cc4921eda7fae57f77f03eb5, 5.10.109, <5.17.2, dca947d4d26dbf925a64a6cfb2ddbc035e831a3d, dd2f8c684da3e226e5ec7a81c89ff5fd4a957a03, 5.16.18, <bc55cfd5718c7c23e5524582e9fa70b4d10f2433, <5.16.19, 47711ff10c7e126702cfa725f6d86ef529d15a5f, 73867cb2bc7dfa7fbd219e53a0b68d253d8fda09

Description

In the Linux kernel, the following vulnerability has been resolved: ALSA: pcm: Fix potential AB/BA lock with buffer_mutex and mmap_lock syzbot caught a potential deadlock between the PCM runtime->buffer_mutex and the mm->mmap_lock. It was brought by the recent fix to cover the racy read/write and other ioctls, and in that commit, I overlooked a (hopefully only) corner case that may take the revert lock, namely, the OSS mmap. The OSS mmap operation exceptionally allows to re-configure the parameters inside the OSS mmap syscall, where mm->mmap_mutex is already held. Meanwhile, the copy_from/to_user calls at read/write operations also take the mm->mmap_lock internally, hence it may lead to a AB/BA deadlock. A similar problem was already seen in the past and we fixed it with a refcount (in commit b248371628aa). The former fix covered only the call paths with OSS read/write and OSS ioctls, while we need to cover the concurrent access via both ALSA and OSS APIs now. This patch addresses the problem above by replacing the buffer_mutex lock in the read/write operations with a refcount similar as we've used for OSS. The new field, runtime->buffer_accessing, keeps the number of concurrent read/write operations. Unlike the former buffer_mutex protection, this protects only around the copy_from/to_user() calls; the other codes are basically protected by the PCM stream lock. The refcount can be a negative, meaning blocked by the ioctls. If a negative value is seen, the read/write aborts with -EBUSY. In the ioctl side, OTOH, they check this refcount, too, and set to a negative value for blocking unless it's already being accessed.

Gravité et risque d'exploitation

CVE-2022-49272 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 0.20 %, ce qui la place devant 9.8 % des CVE référencées.

Que faire ?

  • Vérifiez si Linux (versions <7777744e92a0b30e3e0cce2758d911837011ebd9, <7e9133607e1501c94881be35e118d8f84d96dcb4, <be9813ad2fc8f0885f5ce6925af0d993ce5da4e5, 5.17.1, <9661bf674d6a82b76e4ae424438a8ce1e3ed855d, 08d1807f097a63ea00a7067dad89c1c81cb2115e, <40f4cffbe13a51faf136faf5f9ef6847782cd595, <5.10.110, b3830197aa7413c65767cf5a1aa8775c83f0dbf7, 5.15.32, <5.15.33, 8527c8f052fb42091c6569cb928e472376a4a889, <9017201e8d8c6d1472273361389ed431188584a0, <abedf0d08c79d76da0d6fa0d5dbbc98871dcbc2e, 4d1b0ace2d56dc27cc4921eda7fae57f77f03eb5, 5.10.109, <5.17.2, dca947d4d26dbf925a64a6cfb2ddbc035e831a3d, dd2f8c684da3e226e5ec7a81c89ff5fd4a957a03, 5.16.18, <bc55cfd5718c7c23e5524582e9fa70b4d10f2433, <5.16.19, 47711ff10c7e126702cfa725f6d86ef529d15a5f, 73867cb2bc7dfa7fbd219e53a0b68d253d8fda09) 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.

Références

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