linux-kernel - Re: Is it legal to return positive value when do

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Message-Id: <20101004135524.E8A5.A69D9226@jp.fujitsu.com>
Date:	Mon,  4 Oct 2010 13:59:59 +0900 (JST)
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Cc:	kosaki.motohiro@...fujitsu.com, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: Is it legal to return positive value when do_execve() succeeds?

> Thus, TASK_SIZE == 0xC0000000.
> 
> fs/binfmt_elf.c:
>  77 #define BAD_ADDR(x) ((unsigned long)(x) >= TASK_SIZE)
>  78 
>  79 static int set_brk(unsigned long start, unsigned long end)
>  80 {
>  81         start = ELF_PAGEALIGN(start);
>  82         end = ELF_PAGEALIGN(end);
>  83         if (end > start) {
>  84                 unsigned long addr;
>  85                 down_write(&current->mm->mmap_sem);
>  86                 addr = do_brk(start, end - start);
>  87                 up_write(&current->mm->mmap_sem);
>  88                 if (BAD_ADDR(addr))
>  89                         return addr;
>  90         }
>  91         current->mm->start_brk = current->mm->brk = end;
>  92         return 0;
>  93 }
> 
> Thus, BAD_ADDR(x) is ((unsigned long)(x) >= 0xC0000000).


Can do_brk() return BAD_ADDR() _and_ !IS_ERR_VALUE() value? when?



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