nettle: backport fixes to cfb8_decrypt

cfb8: don't truncate output IV if input is shorter than block size:
https://git.lysator.liu.se/nettle/nettle/commit/f4a9c842621baf5d71aa9cc3989851f44dc46861

Signed-off-by: Daiki Ueno <dueno@redhat.com>

1 files changed, 6 insertions, 4 deletions

diff --git a/lib/nettle/backport/cfb8.c b/lib/nettle/backport/cfb8.c
index e9816feb78..1762192f44 100644
--- a/lib/nettle/backport/cfb8.c
+++ b/lib/nettle/backport/cfb8.c
@@ -110,10 +110,12 @@ cfb8_decrypt(const void *ctx, nettle_cipher_func *f,
       src += i;
       dst += i;
 
-      memcpy(buffer, buffer + block_size, block_size);
-      memcpy(buffer + block_size, src,
-	     length < block_size ? length : block_size);
-
+      if (i == block_size)
+	{
+	  memcpy(buffer, buffer + block_size, block_size);
+	  memcpy(buffer + block_size, src,
+		 length < block_size ? length : block_size);
+	}
     }
 
   memcpy(iv, buffer + i, block_size);