CVE-2022-49272 (GCVE-0-2022-49272)
Vulnerability from cvelistv5
Published
2025-02-26 01:56
Modified
2025-05-04 08:33
Severity ?
Summary
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.
References
Impacted products
Vendor Product Version
Linux Linux Version: 73867cb2bc7dfa7fbd219e53a0b68d253d8fda09
Version: b3830197aa7413c65767cf5a1aa8775c83f0dbf7
Version: 08d1807f097a63ea00a7067dad89c1c81cb2115e
Version: 8527c8f052fb42091c6569cb928e472376a4a889
Version: 47711ff10c7e126702cfa725f6d86ef529d15a5f
Version: 4d1b0ace2d56dc27cc4921eda7fae57f77f03eb5
Version: dd2f8c684da3e226e5ec7a81c89ff5fd4a957a03
Version: dca947d4d26dbf925a64a6cfb2ddbc035e831a3d
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   Linux Linux Version: 5.10.109   ≤
Version: 5.15.32   ≤
Version: 5.16.18   ≤
Version: 5.17.1   ≤
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "include/sound/pcm.h",
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            "sound/core/pcm_native.c"
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          ]
        },
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "include/sound/pcm.h",
            "sound/core/pcm.c",
            "sound/core/pcm_lib.c",
            "sound/core/pcm_native.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "status": "affected",
              "version": "5.17.1",
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        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.110",
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                  "vulnerable": true
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              "negate": false,
              "operator": "OR"
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: pcm: Fix potential AB/BA lock with buffer_mutex and mmap_lock\n\nsyzbot caught a potential deadlock between the PCM\nruntime-\u003ebuffer_mutex and the mm-\u003emmap_lock.  It was brought by the\nrecent fix to cover the racy read/write and other ioctls, and in that\ncommit, I overlooked a (hopefully only) corner case that may take the\nrevert lock, namely, the OSS mmap.  The OSS mmap operation\nexceptionally allows to re-configure the parameters inside the OSS\nmmap syscall, where mm-\u003emmap_mutex is already held.  Meanwhile, the\ncopy_from/to_user calls at read/write operations also take the\nmm-\u003emmap_lock internally, hence it may lead to a AB/BA deadlock.\n\nA similar problem was already seen in the past and we fixed it with a\nrefcount (in commit b248371628aa).  The former fix covered only the\ncall paths with OSS read/write and OSS ioctls, while we need to cover\nthe concurrent access via both ALSA and OSS APIs now.\n\nThis patch addresses the problem above by replacing the buffer_mutex\nlock in the read/write operations with a refcount similar as we\u0027ve\nused for OSS.  The new field, runtime-\u003ebuffer_accessing, keeps the\nnumber of concurrent read/write operations.  Unlike the former\nbuffer_mutex protection, this protects only around the\ncopy_from/to_user() calls; the other codes are basically protected by\nthe PCM stream lock.  The refcount can be a negative, meaning blocked\nby the ioctls.  If a negative value is seen, the read/write aborts\nwith -EBUSY.  In the ioctl side, OTOH, they check this refcount, too,\nand set to a negative value for blocking unless it\u0027s already being\naccessed."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-05-04T08:33:54.705Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/7e9133607e1501c94881be35e118d8f84d96dcb4"
        },
        {
          "url": "https://git.kernel.org/stable/c/40f4cffbe13a51faf136faf5f9ef6847782cd595"
        },
        {
          "url": "https://git.kernel.org/stable/c/9661bf674d6a82b76e4ae424438a8ce1e3ed855d"
        },
        {
          "url": "https://git.kernel.org/stable/c/9017201e8d8c6d1472273361389ed431188584a0"
        },
        {
          "url": "https://git.kernel.org/stable/c/7777744e92a0b30e3e0cce2758d911837011ebd9"
        },
        {
          "url": "https://git.kernel.org/stable/c/abedf0d08c79d76da0d6fa0d5dbbc98871dcbc2e"
        },
        {
          "url": "https://git.kernel.org/stable/c/be9813ad2fc8f0885f5ce6925af0d993ce5da4e5"
        },
        {
          "url": "https://git.kernel.org/stable/c/bc55cfd5718c7c23e5524582e9fa70b4d10f2433"
        }
      ],
      "title": "ALSA: pcm: Fix potential AB/BA lock with buffer_mutex and mmap_lock",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2022-49272",
    "datePublished": "2025-02-26T01:56:18.626Z",
    "dateReserved": "2025-02-26T01:49:39.297Z",
    "dateUpdated": "2025-05-04T08:33:54.705Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1"
}


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