Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: ksmbd: bound smb_check_perm_dacl() ACE walks by DACL size smb_check_perm_dacl() validates that the DACL fits inside the NT security descriptor, but then bounds its two ACE walks by the remaining NTSD length (acl_size) rather than the DACL's declared size (pdacl_size). When pdacl->size is smaller than the trailing NTSD buffer, bytes after the declared DACL boundary - still inside the stored security descriptor - are parsed as ACEs during access checks. A crafted DACL can place an access-granting ACE beyond pdacl->size, and the current code accepts it during SMB2_CREATE access validation, while parse_dacl() and smb_inherit_dacl() stop at pdacl_size. Bound both ACE walks by pdacl_size to match the DACL boundary semantics used elsewhere in the server. Validation: - semantic KUnit harness shows the post-boundary ACE is selected before the fix and rejected (EACCES) after it - linux master (7.2-rc6), x86_64
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected 8f0541186e9ad1b62accc9519cc2b7a7240272a7 before a2051ffe452afad52f580b85a3fd8851933b1e7c; affected 8f0541186e9ad1b62accc9519cc2b7a7240272a7 before a29f57a14c939586d84d7fd6a029bd1fd170098f; affected 8f0541186e9ad1b62accc9519cc2b7a7240272a7 before a4a307d149327dad5fb25187e1b03cebd1b04de6; affected 8f0541186e9ad1b62accc9519cc2b7a7240272a7 before 8e4f75e979c1d9a51b0a48ac33d0cfd5f039ec67; affected 8f0541186e9ad1b62accc9519cc2b7a7240272a7 before 79decd88dd3f0d42e7fb0689b1a7853bfa302459; affected cb69d4d6f709f87c94afa28ae64c501576692171; affected 6e8f4abf584253cbaa596ea4ad13110cf61cd4c9; affected 8e33102309bd6839b2e2e158f93a7b378cb4655d; affected 5.15.62 before 5.16; affected 5.18.18 before 5.19; affected 5.19.2 before 5.20 |
| Linux / Linux | affected 6.0; unaffected 0 before 6.0; unaffected 6.6.157 through 6.6.*; unaffected 6.12.110 through 6.12.*; unaffected 6.18.52 through 6.18.*; unaffected 7.2.6 through 7.2.*; unaffected 7.3 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/a2051ffe452afad52f580b85a3fd8851933b1e7c
- https://git.kernel.org/stable/c/a29f57a14c939586d84d7fd6a029bd1fd170098f
- https://git.kernel.org/stable/c/a4a307d149327dad5fb25187e1b03cebd1b04de6
- https://git.kernel.org/stable/c/8e4f75e979c1d9a51b0a48ac33d0cfd5f039ec67
- https://git.kernel.org/stable/c/79decd88dd3f0d42e7fb0689b1a7853bfa302459