smb3: fix oops in calculating shash_setkey

shash was not being initialized in one place in smb3_calc_signature
and smb2_calc_signature

Reviewed-by: Enzo Matsumiya <ematsumiya@suse.de>
Acked-by: Tom Talpey <tom@talpey.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/cifs/smb2transport.c

@@ -215,7 +215,7 @@ smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server,
 	struct kvec *iov = rqst->rq_iov;
 	struct smb2_hdr *shdr = (struct smb2_hdr *)iov[0].iov_base;
 	struct cifs_ses *ses;
-	struct shash_desc *shash;
+	struct shash_desc *shash = NULL;
 	struct smb_rqst drqst;
 
 	ses = smb2_find_smb_ses(server, le64_to_cpu(shdr->SessionId));
@@ -535,7 +535,7 @@ smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server,
 	unsigned char *sigptr = smb3_signature;
 	struct kvec *iov = rqst->rq_iov;
 	struct smb2_hdr *shdr = (struct smb2_hdr *)iov[0].iov_base;
-	struct shash_desc *shash;
+	struct shash_desc *shash = NULL;
 	struct smb_rqst drqst;
 	u8 key[SMB3_SIGN_KEY_SIZE];