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Message-ID: <51C41448.5060907@cn.fujitsu.com>
Date: Fri, 21 Jun 2013 16:52:24 +0800
From: Zhang Yanfei <zhangyanfei@...fujitsu.com>
To: Daniel Baluta <dbaluta@...acom.com>
CC: Zhang Yanfei <zhangyanfei.yes@...il.com>,
Ghennadi Procopciuc <unix140@...il.com>,
akpm@...ux-foundation.org, js1304@...il.com, rientjes@...gle.com,
minchan@...nel.org, kosaki.motohiro@...fujitsu.com,
linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: fix overflow in alloc_vmap_area
On 06/21/2013 06:51 AM, Daniel Baluta wrote:
> On Thu, Jun 20, 2013 at 7:59 PM, Zhang Yanfei <zhangyanfei.yes@...il.com> wrote:
>> On 06/20/2013 11:12 PM, Ghennadi Procopciuc wrote:
>>> Inserting the following kernel module:
>>>
>>> <snip>
>>>
>>> static int simple_test_init(void)
>>> {
>>> size_t i, j;
>>> void *address;
>>>
>>> for (i = 0 * MB; i< 60 * MB; i += 1 * MB) {
>>> for (j = i; j< i + 1 * MB; j += KB) {
>>> address = vmalloc(j);
>>> vfree(address);
>>> }
>>> }
>>>
>>> return 0;
>>> }
>>>
>>> </snip>
>>>
>>> triggers BUG at mm/vmalloc.c:310 on a x86 machine:
>>>
>>> [ 95.218283] Kernel BUG at c1126cdb [verbose debug info unavailable]
>>> [ 95.218306] invalid opcode: 0000 [#1] SMP
>>> [ 95.218324] Modules linked in: lkma_test(OF+)<snip lots of not tainted modules>
>>> [ 95.218559] Pid: 2419, comm: insmod Tainted: GF O 3.9.0+ #57 Hewlett-Packard HP Compaq 8200 Elite CMT PC/1494
>>> [ 95.218597] EIP: 0060:[<c1126cdb>] EFLAGS: 00010207 CPU: 3
>>> [ 95.218617] EIP is at __insert_vmap_area+0xfb/0x100
>>> [ 95.218635] EAX: f85dc000 EBX: ef05cac0 ECX: f7be08c4 EDX: 00000007
>>> [ 95.218657] ESI: f2ed044c EDI: c1a220b8 EBP: f027bd34 ESP: f027bd14
>>> [ 95.218680] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
>>> [ 95.218699] CR0: 80050033 CR2: b5995118 CR3: 30364000 CR4: 000407f0
>>> [ 95.218721] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
>>> [ 95.218743] DR6: ffff0ff0 DR7: 00000400
>>> [ 95.218758] Process insmod (pid: 2419, ti=f027a000 task=efe64010 task.ti=f027a000)
>>> [ 95.218784] Stack:
>>> [ 95.218792] c177b964 fecfb000 f85e2000 00000000 f85dc000 ffbfe000 f02da1c0 0007f000
>>> [ 95.218829] f027bd7c c112802d c177b9b0 fecfb000 01305000 ffbfe000 00000001 ef05cac0
>>> [ 95.218866] 00000000 00000000 f83fe000 01304fff f83fe000 ffffffff 01305000 ef05c500
>>> [ 95.218903] Call Trace:
>>> [ 95.218915] [<f85e2000>] ? 0xf85e1fff
>>> [ 95.218930] [<f85dc000>] ? 0xf85dbfff
>>> [ 95.218945] [<c112802d>] alloc_vmap_area.isra.16+0x1bd/0x2f0
>>> [ 95.218967] [<c112867f>] __get_vm_area_node.isra.17+0x8f/0x130
>>> [ 95.218988] [<c1128d77>] __vmalloc_node_range+0x57/0x200
>>> [ 95.219009] [<f85f3075>] ? lkma_test_init+0x45/0x70 [lkma_test]
>>> [ 95.219031] [<c1128f82>] __vmalloc_node+0x62/0x70
>>> [ 95.219049] [<f85f3075>] ? lkma_test_init+0x45/0x70 [lkma_test]
>>> [ 95.219071] [<c1129058>] vmalloc+0x38/0x40
>>> [ 95.219087] [<f85f3075>] ? lkma_test_init+0x45/0x70 [lkma_test]
>>> [ 95.219109] [<f85f3075>] lkma_test_init+0x45/0x70 [lkma_test]
>>> [ 95.219131] [<f85f3030>] ? kzalloc+0x10/0x10 [lkma_test]
>>> [ 95.219151] [<c1001222>] do_one_initcall+0x112/0x160
>>> [ 95.219171] [<c15ca3cf>] ? set_section_ro_nx+0x54/0x59
>>> [ 95.219190] [<c1099b69>] load_module+0x1d79/0x2660
>>> [ 95.219209] [<c114721d>] ? create_object+0x19d/0x280
>>> [ 95.219230] [<c109a4c8>] sys_init_module+0x78/0xb0
>>> [ 95.219250] [<c15d9801>] sysenter_do_call+0x12/0x22
>>> [ 95.219268] Code: 39 03 73 0c 8b 3f 89 f0 83 c7 08 e9 3d ff ff ff 8b 46 f4 39 43 04 76 13 8b 3f 89 f0 83 c7 04 e9 29 ff ff ff e8 fb 1b 4a 00 eb ab<0f> 0b 8d 76 00 55 89 e5 56 53 66 66 66 66 90 83 60 0c df 89 c6
>>> [ 95.219415] EIP: [<c1126cdb>] __insert_vmap_area+0xfb/0x100 SS:ESP 0068:f027bd14
>>> [ 95.228313] ---[ end trace e0a1efb2acb97c98 ]---
>>>
>>> A printk placed in __insert_vmap_area will show:
>>>
>>> [ 95.218256] va->va_start=0xfecfb000 tmp_va->va_end=0xf85e2000 va->va_end=0 tmp_va->va_start=0xf85dc000
>>>
>>> and another one, before sum operation in alloc_vmap_area:
>>>
>>> [ 95.218204] addr = 0xfecfb000 size = 19943424 vend = 0xffbfe000
>>>
>>> If after addition the result is smaller than one of the arguments,
>>> then an overflow occurred. In our case there is an obvious overflow.
>>>
>>> Signed-off-by: Ghennadi Procopciuc <unix140@...il.com>
>>> Cc: Daniel Baluta<dbaluta@...acom.com>
>>>
>>> ---
>>> Don't know if this is the right solution, but the bug happens for me in
>>> 3.10-rc6 and 3.9.
>>
>> Hello Ghennadi,
>>
>> Could you please try the below patch to see if it is ok? The patch is based
>> on today's linus' tree.
>
> Hi Zhang,
>
> I have applied your patch and the bug seems to be fixed.
>
Thanks for testing.
> Commit 89699605fe (mm: vmap area cache) suggests to use
> "addr + size < addr" instead of "addr + size - 1 < addr" so I guess
> this is the correct fix.
Ah, yes. I didn't notice the comment in that commit before:)
>From the backtrace of Ghennadi's machine and his printk values,
we should believe the fix is correct.
>
> thanks,
> Daniel.
>
--
Thanks.
Zhang Yanfei
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