[Bug libmudflap/28578] A most simple multithreaded program (practically any multithreaded one) causes mudflap violation

["fche at redhat dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #3 from fche at redhat dot com  2006-11-10 17:43 -------
Some more details.
The data value in question comes from an allocation due to dlerror(),
performed during __mf_init()'s lookup of inteposed dynamic symbols.
Since mudflap is still in __mf_starting_p state, dlerror's calloc()
gets redirected to __mf_0fn_calloc, and gets one of the preallocated
buffers in .bss.

The problem occurs at main thread shutdown, as caused by pthread_exit().
(An ordinary falling-off-the-end does not trigger this problem.)
What happens is that __libc_start_main starts calling funky cleanup functions,
including one __nptl_deallocate_tsd, which results in a free() call
for that value allocated by dlerror().  But now, libmudflap is in normal
non-reentrant state, so this free() is checked, and sure enough is found
not to refer to a corresponding checked allocation call.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28578