full-disclosure - RE: i386 Linux kernel DoS (fixed)

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Message-ID: <BF9651D8732ED311A61D00105A9CA3150B45FC09@berkeley.gci.com>
From: lsawyer at gci.com (Leif Sawyer)
Subject: RE: i386 Linux kernel DoS (fixed)

The fix for 2.4 kernels was posted today by Alan Cox:

Linux 2.4.20-rc1-ac2
o	Ptrace NT flag fix				(Andrea Arcangeli)
o	lcall NT clear fixes				(Petr Vandrovec)
[...]


> -----Original Message-----
> From: Christophe Devine writes:
> 
> Yep; the first version of the DoS I posted on bugtraq was 
> defective and worked only under special conditions (inside
> gdb for example).
[code snipped]
> 
> At the beginning I thought only kernels <= 2.4.18 were 
> affected; but it appeared that both kernels 2.4.19 and
> 2.4.20-rc1 are vulnerable as well.
>
> The flaw seems to be related to the kernel's handling of the 
> nested task (NT) flag inside a lcall7. 
> 
> -- 
> Christophe Devine
>