Wang Yufen wrote:
> If tcp_bpf_sendmsg() is running while sk msg is full, sk_msg_alloc()
> returns -ENOSPC, tcp_bpf_sendmsg() goto wait for memory. If partial memory
> has been alloced by sk_msg_alloc(), that is, msg_tx->sg.size is greater
> than osize after sk_msg_alloc(), memleak occurs. To fix we use
> sk_msg_trim() to release the allocated memory, then goto wait for memory.
Small nit, "sk_msg_alloc() returns -ENOSPC" should be something like, "when
sk_msg_alloc() returns -ENOMEM error,..." That error path is from ENOMEM not
the ENOSPC.
But nice find thanks! I think we might have seen this in a couple cases on
our side as well.
>
> This issue can cause the following info:
> WARNING: CPU: 3 PID: 7950 at net/core/stream.c:208 sk_stream_kill_queues+0xd4/0x1a0
> Call Trace:
> <TASK>
> inet_csk_destroy_sock+0x55/0x110
> __tcp_close+0x279/0x470
> tcp_close+0x1f/0x60
> inet_release+0x3f/0x80
> __sock_release+0x3d/0xb0
> sock_close+0x11/0x20
> __fput+0x92/0x250
> task_work_run+0x6a/0xa0
> do_exit+0x33b/0xb60
> do_group_exit+0x2f/0xa0
> get_signal+0xb6/0x950
> arch_do_signal_or_restart+0xac/0x2a0
> exit_to_user_mode_prepare+0xa9/0x200
> syscall_exit_to_user_mode+0x12/0x30
> do_syscall_64+0x46/0x80
> entry_SYSCALL_64_after_hwframe+0x44/0xae
> </TASK>
>
> WARNING: CPU: 3 PID: 2094 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
> kthread+0xe6/0x110
> ret_from_fork+0x22/0x30
> </TASK>
>
> Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface")
> Signed-off-by: Wang Yufen <wangyufen@xxxxxxxxxx>
> ---
> net/ipv4/tcp_bpf.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
> index 9b9b02052fd3..ac9f491cc139 100644
> --- a/net/ipv4/tcp_bpf.c
> +++ b/net/ipv4/tcp_bpf.c
> @@ -421,8 +421,10 @@ static int tcp_bpf_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
> osize = msg_tx->sg.size;
> err = sk_msg_alloc(sk, msg_tx, msg_tx->sg.size + copy, msg_tx->sg.end - 1);
> if (err) {
> - if (err != -ENOSPC)
> + if (err != -ENOSPC) {
> + sk_msg_trim(sk, msg_tx, osize);
> goto wait_for_memory;
> + }
> enospc = true;
> copy = msg_tx->sg.size - osize;
> }
> --
> 2.25.1
>
Acked-by: John Fastabend <john.fastabend@xxxxxxxxx>
