Subject: Re: 2.6.12-rc1 breaks dosemu
From: Arjan van de Ven <arjan@infradead.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Adrian Bunk <bunk@stusta.de>, linux-kernel@vger.kernel.org,
       linux-msdos@vger.kernel.org, Ingo Molnar <mingo@elte.hu>
In-Reply-To: <200503252354.53154.arnd@arndb.de>
References: <20050320021141.GA4449@stusta.de>
	 <200503251952.33558.arnd@arndb.de>
	 <1111778074.6312.87.camel@laptopd505.fenrus.org>
	 <200503252354.53154.arnd@arndb.de>
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Date: Sat, 26 Mar 2005 09:25:00 +0100
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On Fri, 2005-03-25 at 23:54 +0100, Arnd Bergmann wrote:
> On Freedag 25 März 2005 20:14, Arjan van de Ven wrote:
> 
> > the randomisation patches came in a series of 8 patches (where several
> > were general infrastructure); could you try to disable the individual
> > randomisations one at a time to see which one causes this effect?
> 
> It's caused by top-of-stack-randomization.patch.
> 

looking at the dosemu code; the following bit looks a tad suspect:

unsigned long int stk_ptr, stk_beg, stk_end;
...
 if ((fp = fopen("/proc/self/maps", "r"))) {
    while(fgets(line, 100, fp)) {
      sscanf(line, "%lx-%lx", &stk_beg, &stk_end);
      if (stk_ptr >= stk_beg && stk_ptr < stk_end) {
        stack_init_top = stk_end;
        stack_init_bot = stk_beg;
        c_printf("CPU: Stack bottom %#lx, top %#lx, esp=%#lx\n",
	  stack_init_bot, stack_init_top, stk_ptr);
	break;
      }
    }
    fclose(fp);
  }

do you see that printf somewhere in the logs? 
(afaics stk_ptr never gets initialized; what the code meant probably was 
 if (&stk_ptr >= stk_beg && &stk_ptr < stk_end) {
but the dosemu code is missing the two &'s )

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