smb3: fix signing verification of large reads

[ Upstream commit 46f17d17 ]

Code cleanup in the 5.1 kernel changed the array
passed into signing verification on large reads leading
to warning messages being logged when copying files to local
systems from remote.

   SMB signature verification returned error = -5

This changeset fixes verification of SMB3 signatures of large
reads.
Suggested-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

fs/cifs/smb2pdu.c

@@ -3130,8 +3130,8 @@ smb2_readv_callback(struct mid_q_entry *mid)
 	struct smb2_sync_hdr *shdr =
 				(struct smb2_sync_hdr *)rdata->iov[0].iov_base;
 	unsigned int credits_received = 0;
-	struct smb_rqst rqst = { .rq_iov = rdata->iov,
-				 .rq_nvec = 2,
+	struct smb_rqst rqst = { .rq_iov = &rdata->iov[1],
+				 .rq_nvec = 1,
 				 .rq_pages = rdata->pages,
 				 .rq_offset = rdata->page_offset,
 				 .rq_npages = rdata->nr_pages,