From: Neil Horman <nhorman@openssl.org>
Date: Thu, 29 Feb 2024 14:49:37 +0000 (-0500)
Subject: Fix list appending in win ossl_rcu_call
X-Git-Tag: openssl-3.4.0-alpha1~655
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f39a86281883bd7ff0b3791ed203756d055c001b;p=thirdparty%2Fopenssl.git

Fix list appending in win ossl_rcu_call

The ossl_rcu_call function for windows creates a linked list loop.  fix
it to work like the pthread version properly

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/23671)
---

diff --git a/crypto/threads_pthread.c b/crypto/threads_pthread.c
index 33e225b9957..69b68e5226d 100644
--- a/crypto/threads_pthread.c
+++ b/crypto/threads_pthread.c
@@ -581,10 +581,6 @@ void ossl_synchronize_rcu(CRYPTO_RCU_LOCK *lock)
     uint64_t count;
     struct rcu_cb_item *cb_items, *tmpcb;
 
-    /*
-     * __ATOMIC_ACQ_REL is used here to ensure that we get any prior published
-     * writes before we read, and publish our write immediately
-     */
     pthread_mutex_lock(&lock->write_lock);
     cb_items = lock->cb_items;
     lock->cb_items = NULL;
diff --git a/crypto/threads_win.c b/crypto/threads_win.c
index 873b2bd78c9..6bcbaea10fc 100644
--- a/crypto/threads_win.c
+++ b/crypto/threads_win.c
@@ -357,17 +357,14 @@ void ossl_synchronize_rcu(CRYPTO_RCU_LOCK *lock)
 int ossl_rcu_call(CRYPTO_RCU_LOCK *lock, rcu_cb_fn cb, void *data)
 {
     struct rcu_cb_item *new;
-    struct rcu_cb_item *prev;
 
     new = OPENSSL_zalloc(sizeof(struct rcu_cb_item));
     if (new == NULL)
         return 0;
-    prev = new;
     new->data = data;
     new->fn = cb;
 
-    InterlockedExchangePointer((void * volatile *)&lock->cb_items, prev);
-    new->next = prev;
+    new->next = InterlockedExchangePointer((void * volatile *)&lock->cb_items, new);
     return 1;
 }