Development discussion of WireGuard
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From: Linus Torvalds <>
To: "Jason A. Donenfeld" <>
Subject: Re: Random arrays on kernel stack..
Date: Fri, 29 Jul 2022 10:56:32 -0700	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Fri, Jul 29, 2022 at 10:12 AM Jason A. Donenfeld <> wrote:
> That's a good point. Though note that the current WARN_ON is also
> dependent on DEBUG being set.

Sure. And I think that's ok.

> >  (a) that constant should be a bit lower, so that we *can* use a 1kB
> > stack frame warning on 64-bit architectures
> That's not so much possible. This needs to do a DFS traversal of the
> trie, which means it can be 128 nodes deep since IPv6 addresses have
> 128 bits.

Ahh. Ok. That at least explains where the constant comes from. That
would be a good thing to have somewhere in that definition of the
value ;)

And I agree that malloc() isn't a great choice.

I don't really worry about the stack frame warning (I just raised it
to the same 2k limit I have on my x86-64 box), so doing that 1k
allocation is fine.

And with that constant 128 explained, I don't think it's wrong to not
even test for overflow. We don't test for things that can't happen.

But *if* you test for it for debug purposes, then at that point I
think you need to just do the "warn and don't corrupt stack".


      reply	other threads:[~2022-07-29 17:57 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-28 23:51 Linus Torvalds
2022-07-29 17:12 ` Jason A. Donenfeld
2022-07-29 17:56   ` Linus Torvalds [this message]

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