diff mbox series

[5.4,216/475] bpf, sockmap: Fix double uncharge the mem of sk_msg

Message ID 20220414110901.169014846@linuxfoundation.org
State New
Headers show
Series None | expand

Commit Message

Greg KH April 14, 2022, 1:10 p.m. UTC 
From: Wang Yufen <wangyufen@huawei.com>

[ Upstream commit 2486ab434b2c2a14e9237296db00b1e1b7ae3273 ]

If tcp_bpf_sendmsg is running during a tear down operation, psock may be
freed.

tcp_bpf_sendmsg()
 tcp_bpf_send_verdict()
  sk_msg_return()
  tcp_bpf_sendmsg_redir()
   unlikely(!psock))
     sk_msg_free()

The mem of msg has been uncharged in tcp_bpf_send_verdict() by
sk_msg_return(), and would be uncharged by sk_msg_free() again. When psock
is null, we can simply returning an error code, this would then trigger
the sk_msg_free_nocharge in the error path of __SK_REDIRECT and would have
the side effect of throwing an error up to user space. This would be a
slight change in behavior from user side but would look the same as an
error if the redirect on the socket threw an error.

This issue can cause the following info:
WARNING: CPU: 0 PID: 2136 at net/ipv4/af_inet.c:155 inet_sock_destruct+0x13c/0x260
Call Trace:
 <TASK>
 __sk_destruct+0x24/0x1f0
 sk_psock_destroy+0x19b/0x1c0
 process_one_work+0x1b3/0x3c0
 worker_thread+0x30/0x350
 ? process_one_work+0x3c0/0x3c0
 kthread+0xe6/0x110
 ? kthread_complete_and_exit+0x20/0x20
 ret_from_fork+0x22/0x30
 </TASK>

Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface")
Signed-off-by: Wang Yufen <wangyufen@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20220304081145.2037182-5-wangyufen@huawei.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/ipv4/tcp_bpf.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
index 1584863bbdc1..bcc13368c836 100644
--- a/net/ipv4/tcp_bpf.c
+++ b/net/ipv4/tcp_bpf.c
@@ -296,10 +296,9 @@  int tcp_bpf_sendmsg_redir(struct sock *sk, struct sk_msg *msg,
 	struct sk_psock *psock = sk_psock_get(sk);
 	int ret;
 
-	if (unlikely(!psock)) {
-		sk_msg_free(sk, msg);
-		return 0;
-	}
+	if (unlikely(!psock))
+		return -EPIPE;
+
 	ret = ingress ? bpf_tcp_ingress(sk, psock, msg, bytes, flags) :
 			tcp_bpf_push_locked(sk, msg, bytes, flags, false);
 	sk_psock_put(sk, psock);