lib: Fix strict-aliasing warning in md5 code.

If the compiler detects strict aliasing problems it isn't able to
optimize the code.

Signed-off-by: Andreas Schneider <asn@samba.org>
Reviewed-by: Günther Deschner <gd@samba.org>

1 files changed, 6 insertions, 3 deletions

diff --git a/lib/crypto/md5.c b/lib/crypto/md5.c
index b834c912dfb..352f80f5d11 100644
--- a/lib/crypto/md5.c
+++ b/lib/crypto/md5.c
@@ -137,9 +137,12 @@ _PUBLIC_ void MD5Final(uint8_t digest[16], MD5_CTX *ctx)
     }
     byteReverse(ctx->in, 14);
 
-    /* Append length in bits and transform */
-    ((uint32_t *) ctx->in)[14] = ctx->bits[0];
-    ((uint32_t *) ctx->in)[15] = ctx->bits[1];
+    /* Append length in bits and transform.
+     * Use memcpy to avoid strict-aliasing problems.
+     * This way it can be optimized.
+     */
+    memcpy(&ctx->in[14 * sizeof(uint32_t)], &ctx->bits[0], sizeof(uint32_t));
+    memcpy(&ctx->in[15 * sizeof(uint32_t)], &ctx->bits[1], sizeof(uint32_t));
 
     MD5Transform(ctx->buf, (uint32_t *) ctx->in);
     byteReverse((uint8_t *) ctx->buf, 4);