crypto: ccp - Prevent information leakage on export

[ Upstream commit f709b45e ]

Prevent information from leaking to userspace by doing a memset to 0 of
the export state structure before setting the structure values and copying
it. This prevents un-initialized padding areas from being copied into the
export area.

Cc: <stable@vger.kernel.org> # 3.14.x-
Reported-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>

drivers/crypto/ccp/ccp-crypto-aes-cmac.c

@@ -207,6 +207,9 @@ static int ccp_aes_cmac_export(struct ahash_request *req, void *out)
 	struct ccp_aes_cmac_req_ctx *rctx = ahash_request_ctx(req);
 	struct ccp_aes_cmac_exp_ctx state;
 
+	/* Don't let anything leak to 'out' */
+	memset(&state, 0, sizeof(state));
+
 	state.null_msg = rctx->null_msg;
 	memcpy(state.iv, rctx->iv, sizeof(state.iv));
 	state.buf_count = rctx->buf_count;

drivers/crypto/ccp/ccp-crypto-sha.c

@@ -199,6 +199,9 @@ static int ccp_sha_export(struct ahash_request *req, void *out)
 	struct ccp_sha_req_ctx *rctx = ahash_request_ctx(req);
 	struct ccp_sha_exp_ctx state;
 
+	/* Don't let anything leak to 'out' */
+	memset(&state, 0, sizeof(state));
+
 	state.type = rctx->type;
 	state.msg_bits = rctx->msg_bits;
 	state.first = rctx->first;