cipher: Ensure correct alignment

Unsigned math is required to calculate the current alignment.

Signed-off-by: Doug Nazar <nazard@nazar.ca>

diff --git a/lib/nettle/cipher.c b/lib/nettle/cipher.c
index b41862d1eaf54e146e263100bd042b9a1ff61976..c9c59fb0baf79eea9ffba562d4cf3ea593a9f259 100644 (file)
--- a/lib/nettle/cipher.c
+++ b/lib/nettle/cipher.c
@@ -1096,7 +1096,7 @@ wrap_nettle_cipher_init(gnutls_cipher_algorithm_t algo, void **_ctx,
                        int enc)
 {
        struct nettle_cipher_ctx *ctx;
-       ptrdiff_t cur_alignment;
+       uintptr_t cur_alignment;
        int idx = -1;
        unsigned i;
        uint8_t *ctx_ptr;
@@ -1120,7 +1120,7 @@ wrap_nettle_cipher_init(gnutls_cipher_algorithm_t algo, void **_ctx,
        ctx->enc = enc;
        ctx_ptr = ((uint8_t*)ctx) + sizeof(*ctx);
 
-       cur_alignment = ((ptrdiff_t)ctx_ptr) % 16;
+       cur_alignment = ((uintptr_t)ctx_ptr) % 16;
        if (cur_alignment > 0)
                ctx_ptr += 16 - cur_alignment;