From 740be3b9a6d73336f8c7d540842d0831dc7a808b Mon Sep 17 00:00:00 2001 From: Cong Wang Date: Sat, 26 Oct 2024 11:55:22 -0700 Subject: [PATCH] sock_map: fix a NULL pointer dereference in sock_map_link_update_prog() The following race condition could trigger a NULL pointer dereference: sock_map_link_detach(): sock_map_link_update_prog(): mutex_lock(&sockmap_mutex); ... sockmap_link->map = NULL; mutex_unlock(&sockmap_mutex); mutex_lock(&sockmap_mutex); ... sock_map_prog_link_lookup(sockmap_link->map); mutex_unlock(&sockmap_mutex); Fix it by adding a NULL pointer check. In this specific case, it makes no sense to update a link which is being released. Reported-by: Ruan Bonan Fixes: 699c23f02c65 ("bpf: Add bpf_link support for sk_msg and sk_skb progs") Cc: Yonghong Song Cc: John Fastabend Cc: Jakub Sitnicki Signed-off-by: Cong Wang Link: https://lore.kernel.org/r/20241026185522.338562-1-xiyou.wangcong@gmail.com Signed-off-by: Martin KaFai Lau --- net/core/sock_map.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/core/sock_map.c b/net/core/sock_map.c index 07d6aa4e39ef6..78347d7d25ef3 100644 --- a/net/core/sock_map.c +++ b/net/core/sock_map.c @@ -1760,6 +1760,10 @@ static int sock_map_link_update_prog(struct bpf_link *link, ret = -EINVAL; goto out; } + if (!sockmap_link->map) { + ret = -ENOLINK; + goto out; + } ret = sock_map_prog_link_lookup(sockmap_link->map, &pprog, &plink, sockmap_link->attach_type); -- 2.50.1