CVE-2026-43067

CVE-2026-43067 · ext4: handle wraparound when searching for blocks for indirect mapped blocks

CVSS 9.8 · Critique · EPSS 0,5% · Correctif disponible

dpkg-query -W -f='${source:Package} ${binary:Package} ${Version}\n' | awk '$1=="linux"'

dpkg-query -W -f='${source:Package} ${binary:Package} ${Version}\n' | awk '$1=="linux-hwe-edge"'

dpkg-query -W -f='${source:Package} ${binary:Package} ${Version}\n' | awk '$1=="linux-aws-5.0"'

curl -fsSL https://patchfirst.dev/check.sh | sh

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In the Linux kernel, the following vulnerability has been resolved: ext4: handle wraparound when searching for blocks for indirect mapped blocks Commit 4865c768b563 ("ext4: always allocate blocks only from groups inode can use") restricts what blocks will be allocated for indirect block based files to block numbers that fit within 32-bit block numbers. However, when using a review bot running on the latest Gemini LLM to check this commit when backporting into an LTS based kernel, it raised this concern: If ac->ac_g_ex.fe_group is >= ngroups (for instance, if the goal group was populated via stream allocation from s_mb_last_groups), then start will be >= ngroups. Does this allow allocating blocks beyond the 32-bit limit for indirect block mapped files? The commit message mentions that ext4_mb_scan_groups_linear() takes care to not select unsupported groups. However, its loop uses group = *start, and the very first iteration will call ext4_mb_scan_group() with this unsupported group because next_linear_group() is only called at the end of the iteration. After reviewing the code paths involved and considering the LLM review, I determined that this can happen when there is a file system where some files/directories are extent-mapped and others are indirect-block mapped. To address this, add a safety clamp in ext4_mb_scan_groups().

Publication

2026-05-05T15:23:26.717Z

Mise à jour

2026-10-19T19:06:12.380Z

Pile logicielle: system

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