linux-kernel - Re: [PATCH] module: prevent warning when finit

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Message-ID: <87k3rp4y0n.fsf@rustcorp.com.au>
Date:	Mon, 07 Jan 2013 11:20:16 +1030
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Sasha Levin <sasha.levin@...cle.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] module: prevent warning when finit_module a 0 sized file

Sasha Levin <sasha.levin@...cle.com> writes:
> On 01/02/2013 07:41 PM, Rusty Russell wrote:
>> Sasha Levin <sasha.levin@...cle.com> writes:
>> 
>>> If we try to finit_module on a file sized 0 bytes vmalloc will
>>> scream and spit out a warning.
>>>
>>> Since modules have to be bigger than 0 bytes anyways we can just
>>> check that beforehand and avoid the warning.
>> 
>> Applied, but I added the comment you somehow missed :)
>
> Thanks!
>
> I do have a somewhat related follow-up question:
>
> When init_module() goes through the module loading process, it will try to vmalloc()
> whatever size passed to it by the user, which may cause vmalloc() to scream and shout
> if the size passed from userspace is too big.
>
> Do you think that reading just the header and doing a quick elf_header_check() on
> it before trying to read the entire file would make sense here?

No.  Root asked, we do.  If modprobe wants to check the header, let it.

Cheers,
Rusty.
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