CVE-2024-26720

NameCVE-2024-26720
DescriptionIn the Linux kernel, the following vulnerability has been resolved: mm/writeback: fix possible divide-by-zero in wb_dirty_limits(), again (struct dirty_throttle_control *)->thresh is an unsigned long, but is passed as the u32 divisor argument to div_u64(). On architectures where unsigned long is 64 bytes, the argument will be implicitly truncated. Use div64_u64() instead of div_u64() so that the value used in the "is this a safe division" check is the same as the divisor. Also, remove redundant cast of the numerator to u64, as that should happen implicitly. This would be difficult to exploit in memcg domain, given the ratio-based arithmetic domain_drity_limits() uses, but is much easier in global writeback domain with a BDI_CAP_STRICTLIMIT-backing device, using e.g. vm.dirty_bytes=(1<<32)*PAGE_SIZE so that dtc->thresh == (1<<32)
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)buster4.19.249-2vulnerable
buster (security)4.19.304-1vulnerable
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
linuxsourcebullseye5.10.216-1DSA-5681-1
linuxsourcebookworm6.1.82-1
linuxsource(unstable)6.7.7-1

Notes

https://git.kernel.org/linus/9319b647902cbd5cc884ac08a8a6d54ce111fc78 (6.8-rc3)

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