Subject: RE: [PATCH bpf-next v3 2/4] bpf, sockmap: Fix memleak in tcp_bpf_sendmsg while sk msg is full

From: John Fastabend <[email-masked]>
Date: Fri, 11 Mar 2022 13:55:19 -0800

Wang Yufen wrote:
> If tcp_bpf_sendmsg() is running while sk msg is full. When sk_msg_alloc()
> returns -ENOMEM error, tcp_bpf_sendmsg() goes to 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.
> 
> Other call paths of sk_msg_alloc() have the similar issue, such as
> tls_sw_sendmsg(), so handle sk_msg_trim logic inside sk_msg_alloc(),
> as Cong Wang suggested.
> 
> 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 <[email-masked]>
> Acked-by: John Fastabend <[email-masked]>
> ---

Still LGTM Thanks! Next time drop the ack though if you rewrite the patch
this much. Appreciate the fixes and helpful commit messages though.