crypto: shash - Fix unaligned calculation with short length

When the total length is shorter than the calculated number of unaligned bytes, the call to shash->update breaks. For example, calling crc32c on unaligned buffer with length of 1 can result in a system crash.
Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/shash.c

@@ -77,6 +77,9 @@ static int shash_update_unaligned(struct shash_desc *desc, const u8 *data,
 	u8 buf[shash_align_buffer_size(unaligned_len, alignmask)]
 		__attribute__ ((aligned));
 
+	if (unaligned_len > len)
+		unaligned_len = len;
+
 	memcpy(buf, data, unaligned_len);
 
 	return shash->update(desc, buf, unaligned_len) ?: