Re: [PATCH] Avoid mapping past end of shared object (BZ #18685)

["Carlos O'Donell" <carlos at redhat dot com>]

On 07/16/2015 10:08 PM, Mike Frysinger wrote:
> On 16 Jul 2015 13:17, Carlos O'Donell wrote:
>> On 07/16/2015 12:36 PM, Andreas Schwab wrote:
>>> Perhaps ldd should use a specially compiled ld.so that has a lot of
>>> extra checks added (so that it can be run on arbitrary objects without
>>> creating security hazards).
>>
>> ldd should be a distinct tool that uses libelf, and provides deeper
>> introspection and options. This way we have a second implementation
>> of the loader rules in a cleaner and concise form that we can use
>> to double-check assertions about load order and cycle breakage,
>> and cross-check ld.so changes.
> 
> i agree in having a dedicated/robust tool, but i don't think it means we should 
> disable the trace option in the ldso itself.  having a way to get the actual 
> details out of the ldso i think is still valuable.

Agreed. We need trace to do comparison between eu-ldd and ld.so.
We need trace for developers and for runtime dumps which include
looking at dlopen/dlmopen calls. We need more trace data to look
at namespaces for dlmopen.

Making this trace robust against corrupt binaries is a questionable
endeavor though?
 
> i also don't think glibc should be dependent upon the elfutils package ...

It would be, but only for testing, not building, and in a bootstrap
without eu-ldd you'd just have UNSUPPORTED tests, like if you didn't
have libstdc++-static available for all the C++ tests.

c.