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

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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@gmail.com>
Link: https://patch.msgid.link/20240822181109.2577354-1-aha310510@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Jeongjun Park 2024-08-23 03:11:09 +09:00 committed by Jakub Kicinski
parent e5899b60f5
commit 0fa5e94a18
1 changed files with 2 additions and 3 deletions
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5
drivers/net/xen-netback/hash.c
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@ -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);