Re: NULL pointer at kset_find_obj

From: Rusty Russell
Date: Wed Apr 03 2013 - 02:49:53 EST


David Howells <dhowells@xxxxxxxxxx> writes:
> CAI Qian <caiqian@xxxxxxxxxx> wrote:
>
>> Just booted the latest mainline,
>>
>> [ 35.217698] Request for unknown module key 'Magrathea: Glacier signing
>> key: 8b7774b08bc4ee9637073434c10f0823f6fbe523' err -11
>
> Can you check back earlier in the dmesg to see whether the kernel tried to
> load the key? -11 is presumably -EAGAIN - in which case no such key was found
> (rather than there being a cached lookup failure which is what -ENOKEY would
> indicate). It is possible that you encountered the key-not-yet-valid problem
> due to your h/w clock showing a value prior to the start date on the key.
>
>> [ 35.218511] BUG: unable to handle kernel paging request at ffffffffa03093f0
>> [ 35.218521] IP: [<ffffffff81304710>] kset_find_obj+0x30/0x80
>> ...
>> [ 35.218575] Call Trace:
>> [ 35.218583] [<ffffffff810c827d>] load_module+0xb0d/0x1b00
>> [ 35.218587] [<ffffffff81321880>] ? ddebug_proc_open+0xc0/0xc0
>> [ 35.218593] [<ffffffff81628cd8>] ? page_fault+0x28/0x30
>> [ 35.218596] [<ffffffff810c9347>] sys_init_module+0xd7/0x120
>> [ 35.218601] [<ffffffff81630d59>] system_call_fastpath+0x16/0x1b
>
> I think this bit should be waved in front of Rusty. It looks like it might be
> a bug in error handling code.

It does look like it, but I can't see it. The module code doesn't see
an error (presumably sig_enforce is false), so we continue processing
the module like normal.

Is the module getting corrupted somehow? I don't think the signing
infrastructure is doing it...

Puzzled,
Rusty.
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