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libio vtable verification failures with multiple libcs
- From: Florian Weimer <fweimer at redhat dot com>
- To: GNU C Library <libc-alpha at sourceware dot org>
- Date: Wed, 10 Aug 2016 16:19:12 +0200
- Subject: libio vtable verification failures with multiple libcs
- Authentication-results: sourceware.org; auth=none
This is just a heads-up that the Ruby test suite loads libc.so.6 with an
absolute path, bypassing AT_PLATFORM directories. This can lead to
multiple libc.so.6 copies within the same process:
<https://bugzilla.redhat.com/show_bug.cgi?id=1361037#c17>
There is a test case which creates a FILE * object using one libc and
passes it to fprintf in another libc, which fails vtable verification
because the vtable is not known to fprintf. The dlmopen bypass for
verification does not kick in because dlmopen is not used.
I don't think there is anything we should change on the glibc side as
far as libio is concerned. Fortunately, this is just a Ruby test case
for the Fiddle FFI module. Correct Fiddle use should be unaffected.
(But I do wonder if we should detect that the libc.so.6 soname is loaded
a second time and fail.)
Florian