Re: [PATCH] dlopen: Fix issues related to NODELETE handling and relocations

[Florian Weimer <fweimer at redhat dot com>]

* Adhemerval Zanella:

> On 03/12/2019 14:16, Florian Weimer wrote:
>> The assumption behind the assert in activate_nodelete was wrong:
>> 
>> Inconsistency detected by ld.so: dl-open.c: 459: activate_nodelete:
>> Assertion `!imap->l_init_called || imap->l_type != lt_loaded' failed! (edit)
>> 
>> It can happen that an already-loaded object that is in the local
>> scope is promoted to NODELETE status, via binding to a unique
>> symbol.
>> 
>> Similarly, it is possible that such NODELETE promotion occurs to
>> an already-loaded object from the global scope.  This is why the
>> loop in activate_nodelete has to cover all objects in the namespace
>> of the new object.
>> 
>> In do_lookup_unique, it could happen that the NODELETE status of
>> an already-loaded object was overwritten with a pending NODELETE
>> status.  As a result, if dlopen fails, this could cause a loss of
>> the NODELETE status of the affected object, eventually resulting
>> in an incorrect unload.
>> 
>> Fixes commit f63b73814f74032c0e5d0a83300e3d864ef905e5 ("Remove all
>> loaded objects if dlopen fails, ignoring NODELETE [BZ #20839]").
>> 
>> Tested on x86_64-linux-gnu, i686-linux-gnu, powerpc64le-linux-gnu.
>
> Wouldn't it need to be rebased on top of 'Remove signal blocking from
> dlopen'? I find it confusing trying to review after just reviwing the
> patch that refactors l_nodelete flag.
>
> [1] https://sourceware.org/ml/libc-alpha/2019-12/msg00175.html

No, this patch has to go in first (see the cover letter for the other
patches).

Thank you for helping with reviews!

Florian