CVE-2021-47412 block: don't call rq_qos_ops->done_bio if the bio isn't tracked

2024-05-2115:04:03

Linux

www.cve.org

linux kernel

vulnerability resolved

rq_qos framework

request based driver

bio based driver

error handling

bio_endio()

potential kernel panic

blk_cleanup_queue()

ioc_rqos_done_bio()

blkcg_iolatency_done_bio()

6.3 Medium

AI Score

Confidence

Low

0.0004 Low

EPSS

Percentile

9.0%

JSON

In the Linux kernel, the following vulnerability has been resolved:

block: don’t call rq_qos_ops->done_bio if the bio isn’t tracked

rq_qos framework is only applied on request based driver, so:

rq_qos_done_bio() needn’t to be called for bio based driver
rq_qos_done_bio() needn’t to be called for bio which isn’t tracked,
such as bios ended from error handling code.

Especially in bio_endio():

request queue is referred via bio->bi_bdev->bd_disk->queue, which
may be gone since request queue refcount may not be held in above two
cases
q->rq_qos may be freed in blk_cleanup_queue() when calling into
__rq_qos_done_bio()

Fix the potential kernel panic by not calling rq_qos_ops->done_bio if
the bio isn’t tracked. This way is safe because both ioc_rqos_done_bio()
and blkcg_iolatency_done_bio() are nop if the bio isn’t tracked.

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "block/bio.c"
    ],
    "versions": [
      {
        "version": "1da177e4c3f4",
        "lessThan": "004b8f8a6912",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "1da177e4c3f4",
        "lessThan": "a647a524a467",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "block/bio.c"
    ],
    "versions": [
      {
        "version": "5.14.11",
        "lessThanOrEqual": "5.14.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.15",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]