CVE-2021-47646: Revert "Revert "block, bfq: honor already-setup queue merges""

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

• linux linux kernelbefore 4.19.238
• linux linux kernel4.20 and later · before 5.4.189
• linux linux kernel5.5 and later · before 5.10.110
• linux linux kernel5.11 and later · before 5.15.33
• linux linux kernel5.16 and later · before 5.16.19
• linux linux kernel5.17 and later · before 5.17.2

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

• Linux Linux

  • 5.13affected
  • 430a67f9d6169a7b3e328bceb2ef9542e4153c7c and later · before 65d8a737452e88f251fe5d925371de6d606df613affected · git
  • 430a67f9d6169a7b3e328bceb2ef9542e4153c7c and later · before abc2129e646af7b43025d90a071f83043f1ae76caffected · git
  • 430a67f9d6169a7b3e328bceb2ef9542e4153c7c and later · before 4083925bd6dc89216d156474a8076feec904e607affected · git
  • 430a67f9d6169a7b3e328bceb2ef9542e4153c7c and later · before 15729ff8143f8135b03988a100a19e66d7cb7ecdaffected · git
  • before 5.13not affected · semver
  • 5.15.33 and later · up to and including 5.15.*not affected · semver
  • 5.16.19 and later · up to and including 5.16.*not affected · semver
  • 5.17.2 and later · up to and including 5.17.*not affected · semver
  • 5.18 and laternot affected · original_commit_for_fix

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Other highest-scoring records for the same primary product.

• CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
  90Now
• CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
  89Now
• CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
  85Now

Published before and after this one in the same product

• ← EarlierCVE-2021-47644Feb 26, 2025 · media: staging: media: zoran: move videodev alloc
  22Monitor
• ← EarlierCVE-2021-47645Feb 26, 2025 · media: staging: media: zoran: calculate the right buffer number for zoran_reap_stat_com
  22Monitor
• Later →CVE-2021-47647Feb 26, 2025 · clk: qcom: ipq8074: fix PCI-E clock oops
  22Monitor

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

1free(dev->buf);2/* ... another thread is still running ... */3process(dev->buf);

1lock(&dev->lock);2free(dev->buf);3dev->buf = NULL;4unlock(&dev->lock);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.