[PATCH] Ignore LD_POINTER_GUARD for set-user-ID/set-group-ID binaries.

[Carlos O'Donell]

On 10/08/2015 04:44 AM, Florian Weimer wrote:
> On 09/05/2015 06:39 PM, Hector Marco-Gisbert wrote:
>> A weakness in the dynamic loader have been found, Glibc prior to
>> 2.22.90 are affected. The issue is that the LD_POINTER_GUARD in the
>> environment is not sanitized allowing local attackers easily to bypass
>> the pointer guarding protection on set-user-ID and set-group-ID
>> programs. 
>>
>> Details of the weakness:
>> http://hmarco.org/bugs/glibc_ptr_mangle_weakness.html
>>
>> This patch prevents to disable the pointer guarding protection for
>> set-user-ID/set-group-ID programs.
>>
>> For example, executing "LD_POINTER_GUARD=0 /bin/ping" does not disable
>> the pointer guarding protection unless it is directly executed by root
>> (rUID==eUID).
> 
> Does anyone actually use LD_POINTER_GUARD for debugging?  Maybe we can
> simply retire the environment variable instead.

I vote we remove it. It has long since passed the point of usefullness.
With a proper tunables infrastructure we would have added it in one release
while we tested things, and then removed it one or two releases later.

Cheers,
Carlos.