Description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix out-of-bounds read in smb_check_perm_dacl() The permission-check ACE walk in smb_check_perm_dacl() validates the ACE header size and caps sid.num_subauth at SID_MAX_SUB_AUTHORITIES, but it never checks that ace->size is actually large enough to contain num_subauth sub-authorities before compare_sids() dereferences them. CIFS_SID_BASE_SIZE covers the SID header up to but excluding the sub_auth[] array, and offsetof(struct smb_ace, sid) is the ACE header, so the existing guards only guarantee the 8-byte SID base, i.e. zero sub-authorities. compare_sids() then reads ace->sid.sub_auth[i] for i < min(local_sid->num_subauth, ace->sid.num_subauth). The local comparison SIDs (sid_everyone, sid_unix_NFS_mode, and the id_to_sid() result) always have at least one sub-authority, and an attacker controls the ACE revision and authority bytes (which lie within the in-bounds SID base), so they can match one of those SIDs and force the sub_auth read. A crafted ACE with size == 16 and num_subauth >= 1 placed at the tail of the security descriptor therefore causes a heap out-of-bounds read of up to SID_MAX_SUB_AUTHORITIES * sizeof(__le32) bytes past the pntsd allocation. The security descriptor is loaded by ksmbd_vfs_get_sd_xattr() into a buffer sized exactly to the on-disk data (kzalloc(sd_size) in ndr_decode_v4_ntacl()), so the read lands past the allocation. The malformed descriptor can be stored verbatim via SMB2_SET_INFO (the DACL is not normalised before being written to the security.NTACL xattr) and the read fires on a subsequent SMB2_CREATE access check, making this reachable by an authenticated client on a share that uses ACL xattrs. Add the missing num_subauth-versus-ace_size check, mirroring the identical guards already present in the sibling parsers parse_dacl() and smb_inherit_dacl().
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
282cbbb476b9f35793452bc461934af4c7eca169 to < c7488c85fd822959e9b5c22fbd9e7c8a21caf5e0affectedf20adc4ef7428bc485ee83fd1a592252fb87718b to < 988c93d3bba066d8669143e6ec30bb2be9608d53affected325d4ac11f526cb8964cff14548ccf02d8c756d8 to < 36599894fa8536fefdf1e296c0af71b8b7226859affected95e5aa3c3261da8c95b27d7aecf8ee39b9f86a4c to < d5c81a095c86fe507c032d08f3a8cfc518444927affected90089584b2e25c4510b7b987387b4405f0673ece to < 7627ff8c4f9919f14de562b0160ab4ec9d80b1f7affectedd07b26f39246a82399661936dd0c853983cfade7 to < e36e35660adb9b8ef1435ac359151dda5f094c55affectedd07b26f39246a82399661936dd0c853983cfade7 to < 1ef06004ed4bd6d3ed8c840d9d1a376b66d4935baffected151b1799861fde38087c08f613abc2843ef597b0affected5.15.210 to < 5.15.212affected6.1.176 to < 6.1.177affected6.6.140 to < 6.6.144affected6.12.84 to < 6.12.95affected6.18.25 to < 6.18.38affected7.0.2 to < 7.1affected
Linux Linux
Default version status: affected
7.1affected0 to < 7.1unaffected5.15.212 to ≤ 5.15.*unaffected6.1.177 to ≤ 6.1.*unaffected6.6.144 to ≤ 6.6.*unaffected6.12.95 to ≤ 6.12.*unaffected6.18.38 to ≤ 6.18.*unaffected7.1.3 to ≤ 7.1.*unaffected7.2 to ≤ *unaffected
References
- https://git.kernel.org/stable/c/c7488c85fd822959e9b5c22fbd9e7c8a21caf5e0 ↗
- https://git.kernel.org/stable/c/988c93d3bba066d8669143e6ec30bb2be9608d53 ↗
- https://git.kernel.org/stable/c/36599894fa8536fefdf1e296c0af71b8b7226859 ↗
- https://git.kernel.org/stable/c/d5c81a095c86fe507c032d08f3a8cfc518444927 ↗
- https://git.kernel.org/stable/c/7627ff8c4f9919f14de562b0160ab4ec9d80b1f7 ↗
- https://git.kernel.org/stable/c/e36e35660adb9b8ef1435ac359151dda5f094c55 ↗
- https://git.kernel.org/stable/c/1ef06004ed4bd6d3ed8c840d9d1a376b66d4935b ↗