smb: client: fix OOB read/write from unvalidated DataOffset in coalesce_t2()

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-89633
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-11 20:19:48 UTC
Updated2026-09-11 20:19:48 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: smb: client: fix OOB read/write from unvalidated DataOffset in coalesce_t2() coalesce_t2() computes data pointers directly from server-supplied DataOffset fields with no validation against buffer bounds: data_area_of_tgt = (char *)&pSMBt->hdr.Protocol + get_unaligned_le16(&pSMBt->t2_rsp.DataOffset); data_area_of_src = (char *)&pSMBs->hdr.Protocol + get_unaligned_le16(&pSMBs->t2_rsp.DataOffset); data_area_of_tgt += total_in_tgt; ... memcpy(data_area_of_tgt, data_area_of_src, total_in_src); A small DataOffset can push a pointer below the actual byte area, overwriting header fields; a large one can push it past the buffer end, causing out-of-bounds heap reads (source) or writes (target). The BCC overflow guard does not prevent this: BCC reflects how much data is present, while DataOffset controls where in the buffer it starts. The "validate target area" comment present since the function was first written in 2005 was a placeholder that was never implemented. Add lower- and upper-bound checks for both data pointers before the memcpy, and before any target header fields are modified.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected e4eb295d38b57f4d4b956942a48887eb252d97c6 672cf86aa6aa0fb4012ce4c3b3498df42ad67a4e git Not specified
CNA Linux Linux affected e4eb295d38b57f4d4b956942a48887eb252d97c6 033bc80019f07d158630df4e69b19a49010f54f1 git Not specified
CNA Linux Linux affected e4eb295d38b57f4d4b956942a48887eb252d97c6 6343c1da561962688f203362d80d6a3bfa39fa1b git Not specified
CNA Linux Linux affected 2.6.12 Not specified
CNA Linux Linux unaffected 2.6.12 semver Not specified
CNA Linux Linux unaffected 6.18.51 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.4 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/033bc80019f07d158630df4e69b19a49010f54f1 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/672cf86aa6aa0fb4012ce4c3b3498df42ad67a4e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/6343c1da561962688f203362d80d6a3bfa39fa1b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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