ksmbd: restore DACL size on check_add_overflow() to avoid malformed ACL
Summary
| CVE | CVE-2026-68099 |
|---|---|
| State | PUBLISHED |
| Assigner | Linux |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-08-10 13:19:54 UTC |
| Updated | 2026-08-23 13:16:32 UTC |
| Description | In the Linux kernel, the following vulnerability has been resolved: ksmbd: restore DACL size on check_add_overflow() to avoid malformed ACL check_add_overflow() unconditionally writes the truncated sum into *d even on overflow, per its contract in include/linux/overflow.h. The four check_add_overflow() guards in set_posix_acl_entries_dacl() and set_ntacl_dacl() break out of the ACE-building loops on overflow, but the truncated *size is then consumed downstream at the end of set_ntacl_dacl(): pndacl->size = cpu_to_le16(le16_to_cpu(pndacl->size) + size); This produces an on-wire NT ACL whose pndacl->size under-reports the bytes actually written by the preceding fill_ace_for_sid()/memcpy() calls, yielding a malformed ACL that can trigger out-of-bounds reads when re-parsed by clients or ksmbd itself. Restore *size to its pre-addition value on each overflow branch (via `*size -= ace_sz` / `size -= nt_ace_size`) so that after the break, *size once again holds the cumulative size of the successfully-written ACEs. The committed ACL is then truncated-but-self-consistent rather than malformed. The ksmbd DACL builders are the only check_add_overflow() sites found where an overflow path breaks out of a loop and the destination value is consumed afterward. The other nearby break-style cases either return -EINVAL on overflow (transport_ipc.c) or break without consuming the overflowed destination value afterward (buildid.c). |
Risk And Classification
EPSS: 0.001720000 probability, percentile 0.066820000 (date 2026-08-24)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Linux | Linux | affected 41e53a773db6342ac9a689ee5ba635c31744c9f0 8f3a7a499a7d9bb1c0f33fe78c4a4594d7e307f4 git | Not specified |
| CNA | Linux | Linux | affected 8d5729350b236896f51379588d9a690b7fafb8db f4fcd0c1a243d449307b887fafee23921e9db5ab git | Not specified |
| CNA | Linux | Linux | affected e1955a94b6f17f4b058afa955a6f187eb3ed7615 0bf38372821b1526f31538a7d9811844c55c7f38 git | Not specified |
| CNA | Linux | Linux | affected 5e7b8f3c539d69b2ed5f2408e2f75e68ce7eef43 847ecd4eb3c117c3d2f13f1e7ab506543aad8183 git | Not specified |
| CNA | Linux | Linux | affected 299f962c0b02d048fb45d248b4da493d03f3175d bc90144ce8bb7fcf05ad9417c7adb4e9509d9e13 git | Not specified |
| CNA | Linux | Linux | affected 299f962c0b02d048fb45d248b4da493d03f3175d bbf0a8e931204ecdab494a88d43b0a24a04285c5 git | Not specified |
| CNA | Linux | Linux | affected ef7902be3f215b6bf7babe4dc9dd9a7d57dad7a7 git | Not specified |
| CNA | Linux | Linux | affected 6.1.175 6.1.184 semver | Not specified |
| CNA | Linux | Linux | affected 6.6.136 6.6.148 semver | Not specified |
| CNA | Linux | Linux | affected 6.12.84 6.12.101 semver | Not specified |
| CNA | Linux | Linux | affected 6.18.25 6.18.42 semver | Not specified |
| CNA | Linux | Linux | affected 7.0.2 7.1 semver | Not specified |
| CNA | Linux | Linux | affected 7.1 | Not specified |
| CNA | Linux | Linux | unaffected 7.1 semver | Not specified |
| CNA | Linux | Linux | unaffected 6.1.184 6.1.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.6.148 6.6.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.12.101 6.12.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.18.42 6.18.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.1.6 7.1.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.2 * original_commit_for_fix | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| git.kernel.org/stable/c/0bf38372821b1526f31538a7d9811844c55c7f38 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/bc90144ce8bb7fcf05ad9417c7adb4e9509d9e13 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/847ecd4eb3c117c3d2f13f1e7ab506543aad8183 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/bbf0a8e931204ecdab494a88d43b0a24a04285c5 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/8f3a7a499a7d9bb1c0f33fe78c4a4594d7e307f4 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/f4fcd0c1a243d449307b887fafee23921e9db5ab | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.