From: Pekka Enberg <penberg@kernel.org>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Glauber Costa <glommer@parallels.com>,
Christoph Lameter <cl@linux.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [linux-next-20130422] Bug in SLAB?
Date: Mon, 29 Apr 2013 13:12:51 +0300 [thread overview]
Message-ID: <CAOJsxLFYDC+EDdJrXVnc1qfEyd56bhFLeGE+6Mbhwiq73KQQLQ@mail.gmail.com> (raw)
In-Reply-To: <201304291140.IFJ95894.OFLSFFHQOOMVJt@I-love.SAKURA.ne.jp>
On Mon, Apr 29, 2013 at 5:40 AM, Tetsuo Handa
<penguin-kernel@i-love.sakura.ne.jp> wrote:
> Tetsuo Handa wrote:
>> Also, kmalloc_index() in include/linux/slab.h can return 0 to 26.
>>
>> If (MAX_ORDER + PAGE_SHIFT - 1) > 25 is true and
>> kmalloc_index(64 * 1024 * 1024) is requested (I don't know whether such case
>> happens), kmalloc_caches[26] is beyond the array, for kmalloc_caches[26]
>> allows 0 to 25.
>>
>> If (MAX_ORDER + PAGE_SHIFT - 1) <= 25 is true and
>> kmalloc_index(64 * 1024 * 1024) is requested (I don't know whether such case
>> happens), kmalloc_caches[26] is beyond the array, for
>> kmalloc_caches[MAX_ORDER + PAGE_SHIFT] allows 0 to MAX_ORDER + PAGE_SHIFT - 1.
>>
>> Would you recheck that the array size is correct?
>>
>
> I confirmed (on x86_32) that
>
> volatile unsigned int size = 8 * 1024 * 1024;
> kmalloc(size, GFP_KERNEL);
>
> causes no warning at compile time and returns NULL at runtime. But
>
> unsigned int size = 8 * 1024 * 1024;
> kmalloc(size, GFP_KERNEL);
>
> causes compile time warning
>
> include/linux/slab_def.h:136: warning: array subscript is above array bounds
>
> and runtime bug.
>
> BUG: unable to handle kernel NULL pointer dereference at 00000058
> IP: [<c10b9d76>] kmem_cache_alloc+0x26/0xb0
>
> I confirmed (on x86_32) that
>
> kmalloc(64 * 1024 * 1024, GFP_KERNEL);
>
> causes compile time warning
>
> include/linux/slab_def.h:136: warning: array subscript is above array bounds
>
> and runtime bug.
>
> Kernel BUG at c10b9c5b [verbose debug info unavailable]
> invalid opcode: 0000 [#1] SMP
>
> Also,
>
> volatile unsigned int size = 64 * 1024 * 1024;
> kmalloc(size, GFP_KERNEL);
>
> causes no warning at compile time but runtime bug.
>
> Kernel BUG at c10b9c5b [verbose debug info unavailable]
> invalid opcode: 0000 [#1] SMP
>
> There are kernel modules which expect kmalloc() to return NULL rather than
> oops when the requested size is too large.
Christoph, Glauber, it seems like commit e3366016 ("slab: Use common
kmalloc_index/kmalloc_size functions") is causing some problems here.
Can you please take a look?
Pekka
next prev parent reply other threads:[~2013-04-29 10:12 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-24 12:08 [linux-next-20130422] Bug in bootup code or debug code? Tetsuo Handa
2013-04-25 12:20 ` [linux-next-20130422] Bug in SLAB? Tetsuo Handa
2013-04-29 2:40 ` Tetsuo Handa
2013-04-29 10:12 ` Pekka Enberg [this message]
2013-04-29 14:44 ` Glauber Costa
2013-04-29 14:59 ` Christoph Lameter
2013-04-29 15:16 ` Glauber Costa
2013-04-29 15:46 ` Christoph Lameter
2013-04-29 15:54 ` Glauber Costa
2013-04-29 15:28 ` Tetsuo Handa
2013-04-29 16:16 ` Tetsuo Handa
2013-05-09 12:25 ` Tetsuo Handa
2013-05-09 14:14 ` Christoph Lameter
2013-05-09 21:54 ` Tetsuo Handa
2013-05-10 12:38 ` Tetsuo Handa
2013-05-10 15:57 ` Christoph Lameter
[not found] ` <201305272153.HEH51089.OHFQMOOtFLSFVJ@I-love.SAKURA.ne.jp>
2013-06-17 11:59 ` Tetsuo Handa
2013-04-29 17:48 ` Christoph Lameter
2013-04-29 21:45 ` Tetsuo Handa
2013-04-30 14:26 ` Christoph Lameter
2013-04-30 16:01 ` Tetsuo Handa
2013-04-30 17:27 ` Christoph Lameter
2013-05-01 8:05 ` Pekka Enberg
2013-05-02 15:12 ` Christoph Lameter
2013-05-01 12:14 ` Tetsuo Handa
2013-05-02 11:51 ` Tetsuo Handa
2013-05-02 20:53 ` Christoph Lameter
2013-05-03 8:26 ` Tetsuo Handa
2013-05-03 15:43 ` Christoph Lameter
2013-05-06 6:59 ` Geert Uytterhoeven
2013-05-06 7:27 ` Pekka Enberg
2013-05-03 18:04 ` Christoph Lameter
2013-05-03 18:48 ` Tetsuo Handa
2013-05-03 19:21 ` Christoph Lameter
2013-05-04 0:15 ` Tetsuo Handa
2013-05-06 13:46 ` Christoph Lameter
2013-05-07 10:38 ` Tetsuo Handa
2013-05-07 14:28 ` Christoph Lameter
2013-07-01 20:09 ` Andrew Morton
2013-07-01 21:45 ` Tetsuo Handa
2013-07-01 21:53 ` Andrew Morton
2013-07-02 12:49 ` Tetsuo Handa
2013-07-02 19:12 ` Andrew Morton
2013-07-07 15:58 ` Pekka Enberg
2013-05-06 6:32 ` Pekka Enberg
2013-05-06 13:47 ` Christoph Lameter
2013-05-06 20:24 ` Pekka Enberg
2013-05-07 14:23 ` Christoph Lameter
2013-05-07 14:44 ` Pekka Enberg
2013-05-07 15:40 ` Christoph Lameter
2013-04-30 14:34 ` Christoph Lameter
2013-05-01 8:03 ` Pekka Enberg
2013-05-02 15:13 ` Christoph Lameter
2013-04-30 15:16 ` Fix off by one error in slab.h Christoph Lameter
2013-04-29 2:56 ` [linux-next-20130422] Bug in SLAB? Zhan Jianyu
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