Re: [Qemu-trivial] [Qemu-devel] [PULL 20/22] gdbstub: Handle errors in gdb_accept()

[Paolo Bonzini <pbonzini@redhat.com>]

On 20/05/2018 08:15, Michael Tokarev wrote:
> From: Peter Maydell <peter.maydell@linaro.org>
> 
> In gdb_accept(), we both fail to check all errors (notably
> that from socket_set_nodelay(), as Coverity notes in CID 1005666),
> and fail to return an error status back to our caller. Correct
> both of these things, so that errors in accept() result in our
> stopping with a useful error message rather than ignoring it.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> Reviewed-by: Thomas Huth <thuth@redhat.com>
> Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
> ---
>  gdbstub.c | 16 ++++++++++++----
>  1 file changed, 12 insertions(+), 4 deletions(-)
> 
> diff --git a/gdbstub.c b/gdbstub.c
> index b99980d2e2..e4ece2f5bc 100644
> --- a/gdbstub.c
> +++ b/gdbstub.c
> @@ -1814,7 +1814,7 @@ void gdb_signalled(CPUArchState *env, int sig)
>      put_packet(s, buf);
>  }
>  
> -static void gdb_accept(void)
> +static bool gdb_accept(void)
>  {
>      GDBState *s;
>      struct sockaddr_in sockaddr;
> @@ -1826,7 +1826,7 @@ static void gdb_accept(void)
>          fd = accept(gdbserver_fd, (struct sockaddr *)&sockaddr, &len);
>          if (fd < 0 && errno != EINTR) {
>              perror("accept");
> -            return;
> +            return false;
>          } else if (fd >= 0) {
>              qemu_set_cloexec(fd);
>              break;
> @@ -1834,7 +1834,10 @@ static void gdb_accept(void)
>      }
>  
>      /* set short latency */
> -    socket_set_nodelay(fd);
> +    if (socket_set_nodelay(fd)) {
> +        perror("setsockopt");
> +        return false;

Coverity notes that this leaks fd.

Paolo

> +    }
>  
>      s = g_malloc0(sizeof(GDBState));
>      s->c_cpu = first_cpu;
> @@ -1843,6 +1846,7 @@ static void gdb_accept(void)
>      gdb_has_xml = false;
>  
>      gdbserver_state = s;
> +    return true;
>  }
>  
>  static int gdbserver_open(int port)
> @@ -1883,7 +1887,11 @@ int gdbserver_start(int port)
>      if (gdbserver_fd < 0)
>          return -1;
>      /* accept connections */
> -    gdb_accept();
> +    if (!gdb_accept()) {
> +        close(gdbserver_fd);
> +        gdbserver_fd = -1;
> +        return -1;
> +    }
>      return 0;
>  }
>  
>