CVE-2024-26885

NameCVE-2024-26885
DescriptionIn 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.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
ReferencesDSA-5681-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
linux (PTS)buster4.19.249-2fixed
buster (security)4.19.304-1fixed
bullseye5.10.209-2vulnerable
bullseye (security)5.10.216-1fixed
bookworm6.1.76-1vulnerable
bookworm (security)6.1.90-1fixed
trixie6.7.12-1fixed
sid6.8.9-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
linuxsourcebuster(not affected)
linuxsourcebullseye5.10.216-1DSA-5681-1
linuxsourcebookworm6.1.85-1
linuxsource(unstable)6.7.12-1

Notes

[buster] - linux <not-affected> (Vulnerable code not present)
https://git.kernel.org/linus/281d464a34f540de166cee74b723e97ac2515ec3 (6.9-rc1)

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