Re: [PATCH net] tcp: fix forever orphan socket caused by tcp_abort

[Lorenzo Colitti]

On Thu, Aug 1, 2024 at 10:11 PM Eric Dumazet <edumazet@xxxxxxxxxx> wrote:
> > This patch removes the SOCK_DEAD check in tcp_abort, making it send
> > reset to peer and close the socket accordingly. Preventing the
> > timer-less orphan from happening.
> > [...]
>
> This seems legit, but are you sure these two blamed commits added this bug ?
>
> Even before them, we should have called tcp_done() right away, instead
> of waiting for a (possibly long) timer to complete the job.
>
> This might be important when killing millions of sockets on a busy server.
>
> CC Lorenzo
>
> Lorenzo, do you recall why your patch was testing the SOCK_DEAD flag ?

I think I took it from the original tcp_nuke_addr implementation that
Android used before SOCK_DESTROY and tcp_abort were written. The
oldest reference I could find to that code is this commit that went
into 2.6.39 (!), which already had that check.

https://android.googlesource.com/kernel/common/+/06611218f86dc353d5dd0cb5acac32a0863a2ae5

I expect the check was intended to prevent force-closing the same socket twice.