crypto: tcrypt - fix S/G table for test_aead_speed()

BugLink: http://bugs.launchpad.net/bugs/1756121

commit 5c6ac1d4 upstream.

In case buffer length is a multiple of PAGE_SIZE,
the S/G table is incorrectly generated.
Fix this by handling buflen = k * PAGE_SIZE separately.
Signed-off-by: Robert Baronescu <robert.baronescu@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

crypto/tcrypt.c

@@ -291,11 +291,13 @@ static void sg_init_aead(struct scatterlist *sg, char *xbuf[XBUFSIZE],
 	}
 
 	sg_init_table(sg, np + 1);
-	np--;
+	if (rem)
+		np--;
 	for (k = 0; k < np; k++)
 		sg_set_buf(&sg[k + 1], xbuf[k], PAGE_SIZE);
 
-	sg_set_buf(&sg[k + 1], xbuf[k], rem);
+	if (rem)
+		sg_set_buf(&sg[k + 1], xbuf[k], rem);
 }
 
 static void test_aead_speed(const char *algo, int enc, unsigned int secs,