From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: glommer@parallels.com, cl@linux.com, penberg@kernel.org
Cc: linux-kernel@vger.kernel.org
Subject: Re: [linux-next-20130422] Bug in SLAB?
Date: Mon, 29 Apr 2013 11:40:28 +0900 [thread overview]
Message-ID: <201304291140.IFJ95894.OFLSFFHQOOMVJt@I-love.SAKURA.ne.jp> (raw)
In-Reply-To: <201304252120.GII21814.FMJFtHLOOVQFOS@I-love.SAKURA.ne.jp>
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.
next prev parent reply other threads:[~2013-04-29 2:40 UTC|newest]
Thread overview: 57+ 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 [this message]
2013-04-29 10:12 ` Pekka Enberg
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
2013-04-29 2:56 ` Zhan Jianyu
2013-04-29 3:56 ` Tetsuo Handa
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