AW: [SYSFS] Kernel Null pointer dereference in sysfs_readdir()
From: Duetsch, Thomas LDE1
Date: Wed Jul 12 2006 - 08:38:03 EST
Steven Rostedt wrote:
> On Wed, 2006-07-12 at 13:35 +0200, Duetsch, Thomas LDE1 wrote:
>> Hi,
>>
>> I'm currently working on a custom kernel based on Ingo's -rt patch
>> (2.6.16-rt29).
>>
>> While rebooting my machine, I came across a kernel null pointer
>> dereference in this code segment in fs/sysfs/dir.c, function
>> sysfs_readdir():
>>
>> for (p=q->next; p!= &parent_sd->s_children; p=p->next) {
struct
>> sysfs_dirent *next; const char * name;
>> int len;
>>
>> next = list_entry(p, struct sysfs_dirent,
>> s_sibling);
>> if (!next->s_element)
>> continue;
>>
>> name = sysfs_get_name(next);
>> len = strlen(name);
>> if (next->s_dentry)
>> PROBLEM -> ino = next->s_dentry->d_inode->i_ino;
>> else
>> ino = iunique(sysfs_sb, 2);
>>
>
> Hi Thomas,
>
> Do you have a backtrace to look at? It might be helpful to see what
> functions brought us to this point. Also it might help to determine if
> the problem is vanilla, -rt, or the custom kernel.
>
> Thanks,
>
> -- Steve
Of course, here you go:
<1>BUG: Unable to handle kernel NULL pointer dereference at virtual
address 00000020
<1> printing eip:
<4>c01af187
<1>*pde = 00000000
<0>Oops: 0000 [#1]
<0>PREEMPT
<4>cpu=0 current find:2667
<4>current resource_set: 0
<4> [<c0103fb1>] show_trace+0x21/0x30 (20)
<4> [<c01040ee>] dump_stack+0x1e/0x30 (20)
<4> [<c01044ca>] die+0xba/0x1b0 (68)
<4> [<c01146ed>] do_page_fault+0x37d/0x6d0 (96)
<4> [<c0103b0b>] error_code+0x4f/0x54 (120)
<4> [<c0182a60>] vfs_readdir+0xa0/0xc0 (36)
<4> [<c0182e85>] sys_getdents64+0x75/0xd0 (64)
<4> [<c0102fd9>] syscall_call+0x7/0xb (-8116)
<4>Modules linked in: ide_dump diskdump ipv6 eeprom adm1021 hwmon
i2c_piix4 i2c_core NPCI pcnet32 e100 unix
<0>CPU: 0
<4>EIP: 0060:[<c01af187>] Tainted: P VLI
<4>EFLAGS: 00010286 (2.6.16-rt29-rs_1.0 #1)
<0>EIP is at sysfs_readdir+0xd7/0x240
<0>eax: 00000000 ebx: cfd095a0 ecx: 00000005 edx: cf02be88
<0>esi: cfd0959c edi: ce150c16 ebp: c35b5f50 esp: c35b5f14
<0>ds: 007b es: 007b ss: 0068 preempt: 00000001
<0>Process find (pid: 2667, threadinfo=c35b4000 task=c3686730
wchan=00000000) stack_left=7900 worst_left=-1)
<0>Stack: <0>cfd0959c c3618e60 00000004 00000003 00000000 00000d74
00000004 cfe46a58
<0> 00000005 ce150c10 cf02bb68 cfe46a4c ca844f20 fffffffe cfe47e40
c35b5f74
<0> c0182a60 ca844f20 c35b5f98 c0182d20 cfe47ec8 00001000 ca844f20
c0182d20
<0>Call Trace:
<4>cpu=0 current find:2667
<4>current resource_set: 0
<0> [<c010406a>] show_stack_log_lvl+0xaa/0xe0 (32)
<0> [<c01042ca>] show_registers+0x1ca/0x250 (64)
<0> [<c0104508>] die+0xf8/0x1b0 (68)
<0> [<c01146ed>] do_page_fault+0x37d/0x6d0 (96)
<0> [<c0103b0b>] error_code+0x4f/0x54 (120)
<0> [<c0182a60>] vfs_readdir+0xa0/0xc0 (36)
<0> [<c0182e85>] sys_getdents64+0x75/0xd0 (64)
<0> [<c0102fd9>] syscall_call+0x7/0xb (-8116)
<0>Code: 8d 74 26 00 89 34 24 e8 68 e4 ff ff 89 45 e8 b9 ff ff ff ff 31
c0 8b 7d e8 f2 ae f7 d1 49 89 4d e4 8b 46 20 85 c0 74 74 8b 40 20 <8b>
50 20
0f b7 46 1c 89 54 24 14 8b 4d 08 c1 e8 0c 89 44 24 18
I hope that helps,
Thomas
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