netdev - [PATCH] bpf, sockmap: fix deadlocks in the sockhash and sockmap

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Date: Mon, 18 Sep 2023 17:36:20 +0800
From: Ma Ke <make_ruc2021@....com>
To: john.fastabend@...il.com,
	jakub@...udflare.com,
	davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com
Cc: netdev@...r.kernel.org,
	bpf@...r.kernel.org,
	Ma Ke <make_ruc2021@....com>
Subject: [PATCH] bpf, sockmap: fix deadlocks in the sockhash and sockmap

It seems that elements in sockhash are rarely actively
deleted by users or ebpf program. Therefore, we do not
pay much attention to their deletion. Compared with hash
maps, sockhash only provides spin_lock_bh protection.
This causes it to appear to have self-locking behavior
in the interrupt context, as CVE-2023-0160 points out.

Signed-off-by: Ma Ke <make_ruc2021@....com>
---
 net/core/sock_map.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/core/sock_map.c b/net/core/sock_map.c
index cb11750b1df5..1302d484e769 100644
--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -928,11 +928,12 @@ static long sock_hash_delete_elem(struct bpf_map *map, void *key)
 	struct bpf_shtab_bucket *bucket;
 	struct bpf_shtab_elem *elem;
 	int ret = -ENOENT;
+	unsigned long flags;
 
 	hash = sock_hash_bucket_hash(key, key_size);
 	bucket = sock_hash_select_bucket(htab, hash);
 
-	spin_lock_bh(&bucket->lock);
+	spin_lock_irqsave(&bucket->lock, flags);
 	elem = sock_hash_lookup_elem_raw(&bucket->head, hash, key, key_size);
 	if (elem) {
 		hlist_del_rcu(&elem->node);
@@ -940,7 +941,7 @@ static long sock_hash_delete_elem(struct bpf_map *map, void *key)
 		sock_hash_free_elem(htab, elem);
 		ret = 0;
 	}
-	spin_unlock_bh(&bucket->lock);
+	spin_unlock_irqrestore(&bucket->lock, flags);
 	return ret;
 }
 
-- 
2.37.2