Re: [PATCH 04/16] elfops: add strict bounds checking to get/load_section()

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On 5/18/09, Andreas Robinson <andr345@xxxxxxxxx> wrote:
> On Mon, 2009-05-18 at 17:14 +0100, Alan Jenkins wrote:
>> On 5/18/09, Andreas Robinson <andr345@xxxxxxxxx> wrote:
>> > get_section() and load_section() now return NULL if a section header
>> > is corrupt and points to a block that lies partially or entirely
>> > outside the file data buffer.
>> Great!
>> Just out of interest, do you have any ideas about adding bounds
>> checking for strings?  If I remember correctly, there's still a
>> possibility for crashes if next_string() is used on a section which is
>> missing a final NUL terminator.
> Hmm, you're right ...
> Would it be terribly ugly to have next_string() check that a terminator
> exists at the end of the section and if it doesn't, insert one and then
> write a warning message to the log?

Yeah, terribly ugly :-).  That would require mapping the file as copy
on write (private).  But I _think_ we should be able to run on NOMMU,
where that is not supported.

I would prefer that the program refuse to handle the module if it is
discovered to be corrupt.  I don't think we should try and work around
such corruption.

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