ksmbd: fix slab-out-of-bounds in smb2_allocate_rsp_buf

commit c119f4ed

 upstream.

If ->ProtocolId is SMB2_TRANSFORM_PROTO_NUM, smb2 request size
validation could be skipped. if request size is smaller than
sizeof(struct smb2_query_info_req), slab-out-of-bounds read can happen in
smb2_allocate_rsp_buf(). This patch allocate response buffer after
decrypting transform request. smb3_decrypt_req() will validate transform
request size and avoid slab-out-of-bound in smb2_allocate_rsp_buf().

Reported-by: Norbert Szetei <norbert@doyensec.com>
Cc: stable@vger.kernel.org
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>