Re: [patch] af_unix fix for a panic a DoS and a memory leak [Re: [Real fix] Re: Kernel panic: can't

Alexander Viro (viro@math.psu.edu)
Mon, 1 Mar 1999 08:42:51 -0500 (EST)


On Mon, 1 Mar 1999, Andrea Arcangeli wrote:

> As first the fix from Alexander (the one that uses a gc_current with my
> further cleanup) seems SMP safe and works fine here. At least I am not
> been able to cause any problem to the kernel so far here.
>
> But playing still more the unix domain socket code some minutes ago I
> discovered new critical issues.
>
> I discovered a way to leak memory and cause the machine to stall completly
> in kernel mode for minutes as normal user. Waiting a bit more it will eat
> all memory and the machine will crash badly. It's a plain security issue.

Yes, you can do it. I don't think that ENOMEM is the right return value
here - ECONNREFUSED is more reasonable, IMHO. But yes, we need to limit
the backlog to avoid DoS.

I'm not sure that it's what Michael had triggered - it looked rather like
a dangling pointers with following stomping the random pieces of core.

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