PT-2026-51720 · Linux · Linux
Published
2026-06-24
·
Updated
2026-06-24
·
CVE-2026-52927
None
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In the Linux kernel, the following vulnerability has been resolved:
netfilter: ebtables: fix OOB read in compat mtw from user
Luxiao Xu says:
The function compat mtw from user() converts ebtables extensions from
32-bit user structures to kernel native structures. However, it lacks
proper validation of the user-supplied match size/target size.
When certain extensions are processed, the kernel-side translation
logic may perform memory accesses based on the extension's expected
size. If the user provides a size smaller than what the extension
requires, it results in an out-of-bounds read as reported by KASAN.
This fix introduces a check to ensure match size is at least as large
as the extension's required compatsize. This covers matches, watchers,
and targets, while maintaining compatibility with standard targets.
AFAIU this is relevant for matches that need to go though
match->compat from user() call. Those that use plain memcpy with the
user-provided size are ok because the caller checks that size vs the
start of the next rule entry offset (which itself is checked vs. total
size copied from userspace).
The ->compat from user() callbacks assume they can read compatsize bytes,
so they need this extra check.
Based on an earlier patch from Luxiao Xu.
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Related Identifiers
Affected Products
Linux