Convert hashtable to using ossl_rcu_deref on lookup

The new hashtable has an issue on non-64 bit builds.  We use
CRYPTO_atomic_load to load a pointer value when doing lookups, but that
API relies on the expectation that pointers are 64 bits wide.  On 32 bit
systems, we try to load 64 bits using CRYPTO_atomic_load into a 32 bit
pointer, which overruns our stack

Fix this by no longer using CRYPTO_atomic_load for value fetches from
the hashtable.  Instead use ossl_rcu_deref, whcih operates on void
pointers and is safe on all arches

Reviewed-by: Paul Dale <ppzgs1@gmail.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/24682)

diff --git a/crypto/hashtable/hashtable.c b/crypto/hashtable/hashtable.c
index 67c9b190cf8f22b25ccbd1f6f382da4c425206b7..61d11940a9dcba4c10c23838baabeae136069192 100644 (file)
--- a/crypto/hashtable/hashtable.c
+++ b/crypto/hashtable/hashtable.c
@@ -639,8 +639,7 @@ HT_VALUE *ossl_ht_get(HT *h, HT_KEY *key)
         CRYPTO_atomic_load(&md->neighborhoods[neigh_idx].entries[j].hash,
                            &ehash, h->atomic_lock);
         if (compare_hash(hash, ehash)) {
-            CRYPTO_atomic_load((uint64_t *)&md->neighborhoods[neigh_idx].entries[j].value,
-                               (uint64_t *)&vidx, h->atomic_lock);
+            vidx = ossl_rcu_deref(&md->neighborhoods[neigh_idx].entries[j].value);
             ret = (HT_VALUE *)vidx;
             break;
         }