fkie_cve-2022-50530
Vulnerability from fkie_nvd
Published
2025-10-07 16:15
Modified
2025-10-08 19:38
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: blk-mq: fix null pointer dereference in blk_mq_clear_rq_mapping() Our syzkaller report a null pointer dereference, root cause is following: __blk_mq_alloc_map_and_rqs set->tags[hctx_idx] = blk_mq_alloc_map_and_rqs blk_mq_alloc_map_and_rqs blk_mq_alloc_rqs // failed due to oom alloc_pages_node // set->tags[hctx_idx] is still NULL blk_mq_free_rqs drv_tags = set->tags[hctx_idx]; // null pointer dereference is triggered blk_mq_clear_rq_mapping(drv_tags, ...) This is because commit 63064be150e4 ("blk-mq: Add blk_mq_alloc_map_and_rqs()") merged the two steps: 1) set->tags[hctx_idx] = blk_mq_alloc_rq_map() 2) blk_mq_alloc_rqs(..., set->tags[hctx_idx]) into one step: set->tags[hctx_idx] = blk_mq_alloc_map_and_rqs() Since tags is not initialized yet in this case, fix the problem by checking if tags is NULL pointer in blk_mq_clear_rq_mapping().
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6a440e6d04431e774dc084abe88c106e2a474c1a
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/76dd298094f484c6250ebd076fa53287477b2328
Impacted products
Vendor Product Version


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{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nblk-mq: fix null pointer dereference in blk_mq_clear_rq_mapping()\n\nOur syzkaller report a null pointer dereference, root cause is\nfollowing:\n\n__blk_mq_alloc_map_and_rqs\n set-\u003etags[hctx_idx] = blk_mq_alloc_map_and_rqs\n  blk_mq_alloc_map_and_rqs\n   blk_mq_alloc_rqs\n    // failed due to oom\n    alloc_pages_node\n    // set-\u003etags[hctx_idx] is still NULL\n    blk_mq_free_rqs\n     drv_tags = set-\u003etags[hctx_idx];\n     // null pointer dereference is triggered\n     blk_mq_clear_rq_mapping(drv_tags, ...)\n\nThis is because commit 63064be150e4 (\"blk-mq:\nAdd blk_mq_alloc_map_and_rqs()\") merged the two steps:\n\n1) set-\u003etags[hctx_idx] = blk_mq_alloc_rq_map()\n2) blk_mq_alloc_rqs(..., set-\u003etags[hctx_idx])\n\ninto one step:\n\nset-\u003etags[hctx_idx] = blk_mq_alloc_map_and_rqs()\n\nSince tags is not initialized yet in this case, fix the problem by\nchecking if tags is NULL pointer in blk_mq_clear_rq_mapping()."
    }
  ],
  "id": "CVE-2022-50530",
  "lastModified": "2025-10-08T19:38:32.610",
  "metrics": {},
  "published": "2025-10-07T16:15:37.020",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/6a440e6d04431e774dc084abe88c106e2a474c1a"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/76dd298094f484c6250ebd076fa53287477b2328"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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