On 03/12/2019 18:16, Simon Kelley wrote:
> Ignore previous suggestions, I think I see the problem.
> The code to send a packet is
>  while (retry_send(sendto(daemon->dhcp6fd, daemon->outpacket.iov_base,
>                         save_counter(0), 0, (struct sockaddr *)&from,
>                         sizeof(from))));
> where the length to send comes from the call to save_counter(0), which
> does two things: 1) it returns the length of the packet in the buffer,
> and 2) it zeros the length of the packet in the packet buffer.
> 99% of the time, the while() loop will only execute once, and this will
> be fine. If the syscall gets interrupted, the while loop executes a
> second time and a zero-length packet gets sent.
> The patch to fix this is trivial: change the save_counter() call to
> save_counter(-1)
> I just checked, and this mistake only occurs here, and has been there
> since forever.
> Good spot.
> Simon.

Patch committed:



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