linux-kernel - Re: [PATCH] arch: blackfin: kernel: memory overflow, 'namebuf' length need be more than 256

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Date:	Wed, 29 May 2013 20:06:31 +0800
From:	Chen Gang <gang.chen@...anux.com>
To:	Geert Uytterhoeven <geert@...ux-m68k.org>
CC:	Chen Gang <gang.chen@...anux.com>,
	Mike Frysinger <vapier@...too.org>,
	Anton Vorontsov <anton.vorontsov@...aro.org>,
	Richard Kuo <rkuo@...eaurora.org>,
	Jesper Nilsson <jesper.nilsson@...s.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	David Miller <davem@...emloft.net>,
	"uclinux-dist-devel@...ckfin.uclinux.org" 
	<uclinux-dist-devel@...ckfin.uclinux.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Linux-Arch <linux-arch@...r.kernel.org>
Subject: Re: [PATCH] arch: blackfin: kernel: memory overflow, 'namebuf' length
 need be more than 256

On 05/29/2013 07:30 PM, Geert Uytterhoeven wrote:
>>  void show_regs(struct pt_regs *fp)
>> >  {
>> > -       char buf[150];
>> > +       char buf[512];
> This will increase stack usage a lot. And this function calls decode_address(),
> which allocates another buffer on the stack.
> 

Can it have a risk to cause the related stack used up ? (excuse me, I
don't know the system or thread stack size of blackfin).

If so, we really need save some byes (e.g. buf[300] ...), at least. But
I'm not sure whether it still has the risk too.


> However, as this is in debug code which is (never?) called concurrently, both
> buffers can be made static?
> 

trap_c() may call show_regs(), and can multiple traps occur at the same
time ?

It seems it can (but I am not quite sure): for trap_c() only use stack
variables, and "cpu = raw_smp_processor_id()".



Thanks.
-- 
Chen Gang

Asianux Corporation
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