CVE-2026-99113ksmbd: zero the FS_OBJECT_ID_INFORMATION buffer before filling it in

Official description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: zero the FS_OBJECT_ID_INFORMATION buffer before filling it in smb2_get_info_filesystem() reports 64 bytes for FS_OBJECT_ID_INFORMATION, that is the whole of struct object_id_info, but writes only 46 of them: - objid[] is 16 bytes, and when the volume UUID is not available only sizeof(stfs.f_fsid) (8) bytes are copied into it; - extended_info.version_string[] is STRING_LENGTH (28) bytes, and only strlen("1.1.0") (5) bytes are copied into it. The response buffer is zeroed on allocation (kvzalloc() in smb2_allocate_rsp_buf()), so for a standalone request the remaining 31 bytes are zero. In a compound request they need not be. The offset of the next response is advanced by the length pinned for the previous one, so if a preceding command wrote its reply into the buffer and then failed, smb2_set_err_rsp() pins only the short error response and the next reply lands inside the area that has already been written. Only the header is cleared there: memset((char *)rsp_hdr, 0, sizeof(struct smb2_hdr) + 2); The client then receives up to 31 bytes of a response it was not meant to see, including one that failed with an access denied error. Clear the structure before filling it in. As a side effect version_string is now NUL terminated.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/dbd0f13de153d7094b85034daffa7533d7c2b17a
• https://git.kernel.org/stable/c/90898571fb2c6813c007a62833dd65c00481d44e
• https://git.kernel.org/stable/c/1a35a81c302b36fe4acd35b47b51d5d73e89ba0a
• https://git.kernel.org/stable/c/3fc33ac2125b60f103592b83821f69f3f9aa23ba
• https://git.kernel.org/stable/c/898cb4f2e12a5ddea1b2d821cc642c3100f46da7
• https://git.kernel.org/stable/c/015fffa48e96ca8d73a627445341ccff86b02251
• https://git.kernel.org/stable/c/399aa12450a61a5c73dc77e73f069ece9687c95d