Add memory fences where supported

src/libsodium/crypto_hash/sha256/cp/hash_sha256_cp.c

@@ -156,6 +156,7 @@ SHA256_Pad(crypto_hash_sha256_state *state, uint32_t tmp32[64 + 8])
     unsigned int r;
     unsigned int i;
 
+    ACQUIRE_FENCE;
     r = (unsigned int) ((state->count >> 3) & 0x3f);
     if (r < 56) {
         for (i = 0; i < 56 - r; i++) {
@@ -197,6 +198,7 @@ crypto_hash_sha256_update(crypto_hash_sha256_state *state,
     if (inlen <= 0U) {
         return 0;
     }
+    ACQUIRE_FENCE;
     r = (unsigned long long) ((state->count >> 3) & 0x3f);
 
     state->count += ((uint64_t) inlen) << 3;

src/libsodium/crypto_hash/sha512/cp/hash_sha512_cp.c

@@ -175,6 +175,7 @@ SHA512_Pad(crypto_hash_sha512_state *state, uint64_t tmp64[80 + 8])
     unsigned int r;
     unsigned int i;
 
+    ACQUIRE_FENCE;
     r = (unsigned int) ((state->count[1] >> 3) & 0x7f);
     if (r < 112) {
         for (i = 0; i < 112 - r; i++) {
@@ -218,6 +219,7 @@ crypto_hash_sha512_update(crypto_hash_sha512_state *state,
     if (inlen <= 0U) {
         return 0;
     }
+    ACQUIRE_FENCE;
     r = (unsigned long long) ((state->count[1] >> 3) & 0x7f);
 
     bitlen[1] = ((uint64_t) inlen) << 3;

src/libsodium/crypto_pwhash/scryptsalsa208sha256/pwhash_scryptsalsa208sha256.c

@@ -57,6 +57,7 @@ sodium_strnlen(const char *str, size_t maxlen)
 {
     size_t i = 0U;
 
+    ACQUIRE_FENCE;
     while (i < maxlen && str[i] != 0) {
         i++;
     }

src/libsodium/crypto_sign/ed25519/ref10/open.c

@@ -7,6 +7,7 @@
 #include "crypto_sign_ed25519.h"
 #include "crypto_verify_32.h"
 #include "sign_ed25519_ref10.h"
+#include "private/common.h"
 #include "private/ed25519_ref10.h"
 #include "utils.h"
 
@@ -23,6 +24,7 @@ _crypto_sign_ed25519_verify_detached(const unsigned char *sig,
     ge25519_p3               A;
     ge25519_p2               R;
 
+    ACQUIRE_FENCE;
 #ifdef ED25519_COMPAT
     if (sig[63] & 224) {
         return -1;

src/libsodium/include/sodium/private/common.h

@@ -258,4 +258,10 @@ extern void ct_unpoison(const void *, size_t);
 # define UNPOISON(X, L) (void) 0
 #endif
 
+#ifdef __ATOMIC_ACQUIRE
+# define ACQUIRE_FENCE __atomic_thread_fence(__ATOMIC_ACQUIRE)
+#else
+# define ACQUIRE_FENCE (void) 0
+#endif
+
 #endif

src/libsodium/sodium/codecs.c

@@ -7,6 +7,7 @@
 #include <string.h>
 
 #include "core.h"
+#include "private/common.h"
 #include "utils.h"
 
 /* Derived from original code by CodesInChaos */
@@ -250,6 +251,7 @@ _sodium_base642bin_skip_padding(const char * const b64, const size_t b64_len,
             errno = ERANGE;
             return -1;
         }
+        ACQUIRE_FENCE;
         c = b64[*b64_pos_p];
         if (c == '=') {
             padding_len--;