ksmbd: fix SID memory leak in set_posix_acl_entries_dacl() on overflow

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Summary

CVECVE-2026-64139
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-19 16:17:55 UTC
Updated2026-07-19 16:17:55 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: ksmbd: fix SID memory leak in set_posix_acl_entries_dacl() on overflow Commit 299f962c0b02 ("ksmbd: use check_add_overflow() to prevent u16 DACL size overflow") added check_add_overflow() guards that break out of the ACE-building loops in set_posix_acl_entries_dacl() when the accumulated DACL size would wrap past 65535. However, each iteration allocates a struct smb_sid via kmalloc_obj() at the top of the loop and relies on the kfree(sid) call at the end of the loop body (the 'pass_same_sid' label in the first loop, and the explicit kfree at the tail of the second loop) to release it. The newly introduced 'break' statements bypass those kfree() calls, leaking the sid buffer every time an overflow is detected. A malicious or malformed file with enough POSIX ACL entries to trip the overflow check will leak one or more struct smb_sid allocations on every request that touches the file's DACL, providing a trivial kernel memory exhaustion vector. Free sid before breaking out of the loops to plug the leak.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 8d5729350b236896f51379588d9a690b7fafb8db 9d378e17c864da08c3a4df41dae92cfa6468b00a git Not specified
CNA Linux Linux affected e1955a94b6f17f4b058afa955a6f187eb3ed7615 519fb0a42ce5d7e46935577309fb282a5f2c6ea3 git Not specified
CNA Linux Linux affected 5e7b8f3c539d69b2ed5f2408e2f75e68ce7eef43 0e198f09cb2a554c04de0fea4e790f1250a943ca git Not specified
CNA Linux Linux affected ef7902be3f215b6bf7babe4dc9dd9a7d57dad7a7 eced48cb08f07393a5ea770fdd1026452883c3ad git Not specified
CNA Linux Linux affected 299f962c0b02d048fb45d248b4da493d03f3175d af92ee994cc7f7e83a41c2025f32257a2f82a7ef git Not specified
CNA Linux Linux affected 41e53a773db6342ac9a689ee5ba635c31744c9f0 git Not specified
CNA Linux Linux affected 6.1.175 6.2 semver Not specified
CNA Linux Linux affected 6.6.136 6.6.142 semver Not specified
CNA Linux Linux affected 6.12.84 6.12.92 semver Not specified
CNA Linux Linux affected 6.18.25 6.18.34 semver Not specified
CNA Linux Linux affected 7.0.2 7.0.11 semver Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/af92ee994cc7f7e83a41c2025f32257a2f82a7ef 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/eced48cb08f07393a5ea770fdd1026452883c3ad 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/9d378e17c864da08c3a4df41dae92cfa6468b00a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/0e198f09cb2a554c04de0fea4e790f1250a943ca 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/519fb0a42ce5d7e46935577309fb282a5f2c6ea3 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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