diff options
authorXiyu Yang <xiyuyang19@fudan.edu.cn>2020-04-26 11:35:15 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-05-20 08:20:39 +0200
commit9d2487643b4fb8391f89c2e0fb6554991852c0a3 (patch)
parentd41689a34a9d3e417c53b24bb24bf16086671ae2 (diff)
bpf: Fix sk_psock refcnt leak when receiving message
commit 18f02ad19e2c2a1d9e1d55a4e1c0cbf51419151c upstream. tcp_bpf_recvmsg() invokes sk_psock_get(), which returns a reference of the specified sk_psock object to "psock" with increased refcnt. When tcp_bpf_recvmsg() returns, local variable "psock" becomes invalid, so the refcount should be decreased to keep refcount balanced. The reference counting issue happens in several exception handling paths of tcp_bpf_recvmsg(). When those error scenarios occur such as "flags" includes MSG_ERRQUEUE, the function forgets to decrease the refcnt increased by sk_psock_get(), causing a refcnt leak. Fix this issue by calling sk_psock_put() or pulling up the error queue read handling when those error scenarios occur. Fixes: e7a5f1f1cd000 ("bpf/sockmap: Read psock ingress_msg before sk_receive_queue") Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn> Signed-off-by: Xin Tan <tanxin.ctf@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com> Link: https://lore.kernel.org/bpf/1587872115-42805-1-git-send-email-xiyuyang19@fudan.edu.cn Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 6 insertions, 3 deletions
diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
index 19bd10e6ab83..69b025408390 100644
--- a/net/ipv4/tcp_bpf.c
+++ b/net/ipv4/tcp_bpf.c
@@ -121,14 +121,17 @@ int tcp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
struct sk_psock *psock;
int copied, ret;
+ if (unlikely(flags & MSG_ERRQUEUE))
+ return inet_recv_error(sk, msg, len, addr_len);
psock = sk_psock_get(sk);
if (unlikely(!psock))
return tcp_recvmsg(sk, msg, len, nonblock, flags, addr_len);
- if (unlikely(flags & MSG_ERRQUEUE))
- return inet_recv_error(sk, msg, len, addr_len);
if (!skb_queue_empty(&sk->sk_receive_queue) &&
- sk_psock_queue_empty(psock))
+ sk_psock_queue_empty(psock)) {
+ sk_psock_put(sk, psock);
return tcp_recvmsg(sk, msg, len, nonblock, flags, addr_len);
+ }
copied = __tcp_bpf_recvmsg(sk, psock, msg, len, flags);