| From 18f02ad19e2c2a1d9e1d55a4e1c0cbf51419151c Mon Sep 17 00:00:00 2001 |
| From: Xiyu Yang <xiyuyang19@fudan.edu.cn> |
| Date: Sun, 26 Apr 2020 11:35:15 +0800 |
| Subject: bpf: Fix sk_psock refcnt leak when receiving message |
| |
| From: Xiyu Yang <xiyuyang19@fudan.edu.cn> |
| |
| 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> |
| |
| --- |
| net/ipv4/tcp_bpf.c | 9 ++++++--- |
| 1 file changed, 6 insertions(+), 3 deletions(-) |
| |
| --- a/net/ipv4/tcp_bpf.c |
| +++ b/net/ipv4/tcp_bpf.c |
| @@ -121,14 +121,17 @@ int tcp_bpf_recvmsg(struct sock *sk, str |
| 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); |
| + } |
| lock_sock(sk); |
| msg_bytes_ready: |
| copied = __tcp_bpf_recvmsg(sk, psock, msg, len, flags); |