CVE-2026-97561 — smb: client: honor forceuid/forcegid when mapping SIDs to uid/gid

Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

smb: client: honor forceuid/forcegid when mapping SIDs to uid/gid

When the administrator mounts with forceuid or forcegid (uid=/gid= mount options), they expect all files to appear owned by the specified user/group. However, several code paths unconditionally called sid_to_id() to overwrite cf_uid/cf_gid with server-provided values, ignoring the administrator's explicit override:

- smb311_posix_info_to_fattr() (stat via POSIX extensions) - cifs_posix_to_fattr() (readdir via POSIX extensions) - parse_sec_desc() (CIFS ACL ownership mapping)

This allowed an untrusted server to dictate local file ownership even when the mount was configured to force specific uid/gid values.

Fix all three call sites to check CIFS_MOUNT_OVERR_UID and CIFS_MOUNT_OVERR_GID before calling sid_to_id(), following the same pattern already used by cifs_unix_basic_to_fattr() for unix extensions.

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CVE-2026-97561 — smb: client: honor forceuid/forcegid when mapping SIDs to uid/gid