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SubjectRe: Simple kernel attack using socketpair. easy, 100% reproductiblle, works under guest. no way to protect :(
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Le jeudi 25 novembre 2010 à 07:28 +0100, Eric Dumazet a écrit :

>
> Since you obviously read recent mails on this subject yesterday, why
> dont you Cc netdev ?
>
> There is a very easy way to protect against this actually.
>
> A patch was posted yesterday, and need some adjustements.
>
>
> diff --git a/net/unix/garbage.c b/net/unix/garbage.c
> index c8df6fd..40df93d 100644
> --- a/net/unix/garbage.c
> +++ b/net/unix/garbage.c
> @@ -259,9 +259,16 @@ static void inc_inflight_move_tail(struct unix_sock *u)
> }
>
> static bool gc_in_progress = false;
> +#define UNIX_INFLIGHT_TRIGGER_GC 2000
>
> void wait_for_unix_gc(void)
> {
> + /*
> + * If number of inflight sockets is insane,
> + * force a garbage collect right now.
> + */
> + if (unix_tot_inflight > UNIX_INFLIGHT_TRIGGER_GC && !gc_in_progress)
> + unix_gc();
> wait_event(unix_gc_wait, gc_in_progress == false);
> }
>
>

Hmm... it seems its another problem, chains are very long so we hit a
NMI watchdog.

I guess we should limit to a very small number, like 64, or rewrite the
garbage collector to a better algo.



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