commit 6df164e29b upstream.
In xdr_stream_decode_opaque_auth(), zero-length checksum.len causes
checksum.data to be set to NULL. This triggers a NPD when accessing
checksum.data in gss_krb5_verify_mic_v2(). This patch ensures that
the value of checksum.len is not less than XDR_UNIT.
Fixes: 0653028e8f ("SUNRPC: Convert gss_verify_header() to use xdr_stream")
Cc: stable@kernel.org
Signed-off-by: Lei Lu <llfamsec@gmail.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>