ksmbd: fix OOB write in QUERY_INFO for compound requests

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Summary

CVECVE-2026-31432
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-22 09:16:21 UTC
Updated2026-04-22 09:16:21 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: ksmbd: fix OOB write in QUERY_INFO for compound requests When a compound request such as READ + QUERY_INFO(Security) is received, and the first command (READ) consumes most of the response buffer, ksmbd could write beyond the allocated buffer while building a security descriptor. The root cause was that smb2_get_info_sec() checked buffer space using ppntsd_size from xattr, while build_sec_desc() often synthesized a significantly larger descriptor from POSIX ACLs. This patch introduces smb_acl_sec_desc_scratch_len() to accurately compute the final descriptor size beforehand, performs proper buffer checking with smb2_calc_max_out_buf_len(), and uses exact-sized allocation + iov pinning.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d d48c64fb80ad78b3dd29fb7d79b6ec7bd72bfc09 git Not specified
CNA Linux Linux affected e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d 075ea208c648cc2bcd616295b711d3637c61de45 git Not specified
CNA Linux Linux affected e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d 515c2daab46021221bdf406bef19bc90a44ec617 git Not specified
CNA Linux Linux affected e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d fda9522ed6afaec45cabc198d8492270c394c7bc git Not specified
CNA Linux Linux affected f2283680a80571ca82d710bc6ecd8f8beac67d63 git Not specified
CNA Linux Linux affected 9f297df20d93411c0b4ddad7f88ba04a7cd36e77 git Not specified
CNA Linux Linux affected 6.6 Not specified
CNA Linux Linux unaffected 6.6 semver Not specified
CNA Linux Linux unaffected 6.12.81 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.22 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19.12 6.19.* semver Not specified
CNA Linux Linux unaffected 7.0 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/075ea208c648cc2bcd616295b711d3637c61de45 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/d48c64fb80ad78b3dd29fb7d79b6ec7bd72bfc09 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/515c2daab46021221bdf406bef19bc90a44ec617 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/fda9522ed6afaec45cabc198d8492270c394c7bc 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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