From: Jeongjun Park <aha310510@xxxxxxxxx> [ Upstream commit 0fa5e94a1811d68fbffa0725efe6d4ca62c03d12 ] During the list_for_each_entry_rcu iteration call of xenvif_flush_hash, kfree_rcu does not exist inside the rcu read critical section, so if kfree_rcu is called when the rcu grace period ends during the iteration, UAF occurs when accessing head->next after the entry becomes free. Therefore, to solve this, you need to change it to list_for_each_entry_safe. Signed-off-by: Jeongjun Park <aha310510@xxxxxxxxx> Link: https://patch.msgid.link/20240822181109.2577354-1-aha310510@xxxxxxxxx Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/net/xen-netback/hash.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/net/xen-netback/hash.c b/drivers/net/xen-netback/hash.c index ff96f22648efd..45ddce35f6d2c 100644 --- a/drivers/net/xen-netback/hash.c +++ b/drivers/net/xen-netback/hash.c @@ -95,7 +95,7 @@ static u32 xenvif_new_hash(struct xenvif *vif, const u8 *data, static void xenvif_flush_hash(struct xenvif *vif) { - struct xenvif_hash_cache_entry *entry; + struct xenvif_hash_cache_entry *entry, *n; unsigned long flags; if (xenvif_hash_cache_size == 0) @@ -103,8 +103,7 @@ static void xenvif_flush_hash(struct xenvif *vif) spin_lock_irqsave(&vif->hash.cache.lock, flags); - list_for_each_entry_rcu(entry, &vif->hash.cache.list, link, - lockdep_is_held(&vif->hash.cache.lock)) { + list_for_each_entry_safe(entry, n, &vif->hash.cache.list, link) { list_del_rcu(&entry->link); vif->hash.cache.count--; kfree_rcu(entry, rcu); -- 2.43.0
