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Message-ID: <Pine.LNX.4.61.0610222306240.22903@yvahk01.tjqt.qr>
Date: Sun, 22 Oct 2006 23:09:35 +0200 (MEST)
From: Jan Engelhardt <jengelh@...ux01.gwdg.de>
To: Pekka Enberg <penberg@...helsinki.fi>
cc: Amit Choudhary <amit2030@...oo.com>, linux-kernel@...r.kernel.org
Subject: Re: Hopefully, kmalloc() will always succeed, but if it doesn't
then....
>> So, if memory allocation to 'a' fails, it is going to kfree 'b'. But since
>> 'b'
>> is not initialized, kfree may crash (unless DEBUG is defined).
... in which case we will be notified:
$ cat test.c
#include <linux/slab.h>
void func(void) {
char *a, *b;
if((a = kmalloc(10, GFP_KERNEL)) == NULL)
goto err;
if((b = kmalloc(10, GFP_KERNEL)) == NULL)
goto err;
err:
kfree(a);
kfree(b);
return;
}
$ make -C /erk/kernel/linux-2.6.19-rc2 M=$PWD
CC [M] /dev/shm/test.o
/dev/shm/test.c: In function ‘func’:
/dev/shm/test.c:4: warning: ‘b’ may be used uninitialized in this
function
Compared to the whole source tree, the kernel has very few "may be
uninitialized" spots. And stochastically, it is quite unlikely that all
of them are caused by a construct like the above.
>> I have seen the same case at many places when allocating in a loop.
>
> So you found a bug. Why not send a patch to fix it?
-`J'
--
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