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Commit 3c4423b0 authored by Jeongjun Park's avatar Jeongjun Park Committed by Greg Kroah-Hartman
Browse files

net/xen-netback: prevent UAF in xenvif_flush_hash() 



commit 0fa5e94a1811d68fbffa0725efe6d4ca62c03d12 upstream.

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: default avatarJeongjun Park <aha310510@gmail.com>
Link: https://patch.msgid.link/20240822181109.2577354-1-aha310510@gmail.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
Signed-off-by: default avatarHagar Hemdan <hagarhem@amazon.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 4b978070

drivers/net/xen-netback/hash.c

+2 −3
Original line number Diff line number Diff line
@@ -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);