This is a note to let you know that I've just added the patch titled
bpf, sockmap: Fix double uncharge the mem of sk_msg
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
bpf-sockmap-fix-double-uncharge-the-mem-of-sk_msg.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit bc71ed83483d8c50d9d1a31129d2d9c4e7ffeeba
Author: Wang Yufen <wangyufen@xxxxxxxxxx>
Date: Fri Mar 4 16:11:45 2022 +0800
bpf, sockmap: Fix double uncharge the mem of sk_msg
[ 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@xxxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Acked-by: John Fastabend <john.fastabend@xxxxxxxxx>
Link: https://lore.kernel.org/bpf/20220304081145.2037182-5-wangyufen@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
index 304800c60427..1cdcb4df0eb7 100644
--- a/net/ipv4/tcp_bpf.c
+++ b/net/ipv4/tcp_bpf.c
@@ -138,10 +138,9 @@ 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);
