Re: [1/2] 2.6.22-rc7: known regressions

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Looks input-related..

On Thu, 5 Jul 2007, David Woodhouse wrote:
> 
> Hm, it's not something new. It's an oops I saw occasionally in 2.6.21-rc
> too, whenever we had CONFIG_SYSFS_DEPRECATED set.
> 
>  Unable to handle kernel paging request for data at address 0x6b6b6b6b

Ok, that 0x6b is obviously the kfree() poisoning, ie it looks like a 
use-after-free problem with a pointer being loaded from a structure that 
had been free'd-

And the trace seems to be (ignore the unreliable one):

>  NIP [c001870c] strlen+0x4/0x18
>  LR [c0134fec] kobject_get_path+0x34/0xc4
>  Call Trace:
>  [eed5be90] [c01d5124] class_uevent+0xac/0x1bc
>  [eed5bed0] [c01357e4] kobject_uevent_env+0x23c/0x460
>  [eed5bf20] [c01d485c] class_device_del+0x178/0x1a0
>  [eed5bf40] [c01d489c] class_device_unregister+0x18/0x30
>  [eed5bf60] [c021f820] input_unregister_device+0xf4/0x130
>  [eed5bf70] [c0242f4c] hidinput_disconnect+0x2c/0x60
>  [eed5bf90] [f27f2bac] hidp_session+0x550/0x584 [hidp]
>  [eed5bff0] [c0013e28] kernel_thread+0x44/0x60

Where we have a few missing functions due to inlining, ie the real 
sequence seems to be:

class_device_del ->
  kobject_uevent_env ->
    class_uevent ->
      kobject_get_path ->
	get_kobj_path_length ->
	  parent = kobj;
	  do {
	    strlen(parent->k_name /* kobject_name(parent) */);
	    parent = parent->parent;
	  } while (parent);

so either the kobj or one of it's parents had already been freed when it 
was unregistered due to the disconnect.

I'm not seeing any reference counting or other protection for the device 
("input") on "hid->inputs" list. But I don't know the code. Dmitry? Jiri?

		Linus
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]
  Powered by Linux