Description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: reject undersized DACLs before parsing ACEs parse_dacl() limits the attacker-controlled ACE count by comparing it with the number of minimal ACEs that fit in the DACL size. The DACL size field is 16 bits, but the expression subtracts sizeof(struct smb_acl). Because sizeof() is unsigned, a DACL size smaller than the ACL header underflows to a large size_t. A malicious client can reach this with: SMB2_SET_INFO (InfoType=SMB2_O_INFO_SECURITY) -> smb2_set_info_sec() -> set_info_sec() -> parse_sec_desc() -> parse_dacl() -> init_acl_state(..., 0xffff) -> init_acl_state(..., 0xffff) -> kmalloc_objs(..., 0xffff) Thus a malformed security descriptor can make num_aces pass the guard and drive large temporary ACL state and pointer-array allocations. Reject DACLs smaller than struct smb_acl before doing the subtraction, so the ACE count check cannot be bypassed by the underflow.
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
e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 to < 8dc949061e35427433feac3ebe5ec089f2aa857eaffectede2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 to < 16fb65ec15fe7c90f50a2115854bfd9a032d4023affectede2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 to < 282847c0cf22f2e961155ac8e42f6eeab7e16049affectede2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 to < d020e7f27bf65eecd3805404702f716b2b6d9e73affectede2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 to < 15a9e9b8f7f5d7f380ae54c6f5bcbc0bdcb0f3cdaffectede2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 to < 60908f7ebcd9b6cde74ad5711fab0f49c7970949affected
Linux Linux
Default version status: affected
5.15affected0 to < 5.15unaffected6.1.191 to ≤ 6.1.*unaffected6.6.145 to ≤ 6.6.*unaffected6.12.97 to ≤ 6.12.*unaffected6.18.40 to ≤ 6.18.*unaffected7.1.5 to ≤ 7.1.*unaffected7.2 to ≤ *unaffected
References
- https://git.kernel.org/stable/c/8dc949061e35427433feac3ebe5ec089f2aa857e ↗
- https://git.kernel.org/stable/c/16fb65ec15fe7c90f50a2115854bfd9a032d4023 ↗
- https://git.kernel.org/stable/c/282847c0cf22f2e961155ac8e42f6eeab7e16049 ↗
- https://git.kernel.org/stable/c/d020e7f27bf65eecd3805404702f716b2b6d9e73 ↗
- https://git.kernel.org/stable/c/15a9e9b8f7f5d7f380ae54c6f5bcbc0bdcb0f3cd ↗
- https://git.kernel.org/stable/c/60908f7ebcd9b6cde74ad5711fab0f49c7970949 ↗