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| author | Xiyu Yang <xiyuyang19@fudan.edu.cn> | 2020-04-26 06:35:15 +0300 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2020-04-28 00:04:05 +0300 |
| commit | 18f02ad19e2c2a1d9e1d55a4e1c0cbf51419151c (patch) | |
| tree | 2469e6fd5815c9d482d05637742e15ce603b3e86 /net/ipv4 | |
| parent | 37255e7a8f470a7d9678be89c18ba15d6ebf43f7 (diff) | |
| download | linux-18f02ad19e2c2a1d9e1d55a4e1c0cbf51419151c.tar.xz | |
bpf: Fix sk_psock refcnt leak when receiving message
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
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/tcp_bpf.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c index 5a05327f97c1..ff96466ea6da 100644 --- a/net/ipv4/tcp_bpf.c +++ b/net/ipv4/tcp_bpf.c @@ -262,14 +262,17 @@ static 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); + } lock_sock(sk); msg_bytes_ready: copied = __tcp_bpf_recvmsg(sk, psock, msg, len, flags); |