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CVE-2024-26885

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix DEVMAP_HASH overflow check on 32-bit arches The devmap code allocates a number hash bucket…

Published Apr 17, 2024 · updated Oct 15, 2026 · linux linux kernel

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix DEVMAP_HASH overflow check on 32-bit arches The devmap code allocates a number hash buckets equal to the next power of two of the max_entries value provided when creating the map. When rounding up to the next power of two, the 32-bit variable storing the number of buckets can overflow, and the code checks for overflow by checking if the truncated 32-bit value is equal to 0. However, on 32-bit arches the rounding up itself can overflow mid-way through, because it ends up doing a left-shift of 32 bits on an unsigned long value. If the size of an unsigned long is four bytes, this is undefined behaviour, so there is no guarantee that we'll end up with a nice and tidy 0-value at the end. Syzbot managed to turn this into a crash on arm32 by creating a DEVMAP_HASH with max_entries > 0x80000000 and then trying to update it. Fix this by moving the overflow check to before the rounding up operation.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Apr 17, 2024 · NIST NVD

    Detected

    In the Linux kernel, the following vulnerability has been resolved: bpf: Fix DEVMAP_HASH overflow check on 32-bit arches The devmap code allocates a number hash buckets equal to the next power of two of the max_entries value provided when creating the map. When rounding up to the next power of two, the 32-bit variable storing the number of buckets can overflow, and the code checks for overflow by

  2. Oct 15, 2026 · NIST NVD

    Updated

    In the Linux kernel, the following vulnerability has been resolved: bpf: Fix DEVMAP_HASH overflow check on 32-bit arches The devmap code allocates a number hash buckets equal to the next power of two of the max_entries value provided when creating the map. When rounding up to the next power of two, the 32-bit variable storing the number of buckets can overflow, and the code checks for overflow by

Affected

  • cpe linux/linux kernelversion unspecified

Sources

  • CVE.orgVulnerability recordCVE-2024-26885

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2024-26885

    30-day exploitation probability 0.3%

    first.org
  • NIST NVDVulnerability recordCVE-2024-26885

    In the Linux kernel, the following vulnerability has been resolved: bpf: Fix DEVMAP_HASH overflow check on 32-bit arches The devmap code allocates a number hash buckets equal to the next power of two of the max_entries value provided when creating the map. When rounding up to t

    nvd.nist.gov

References