malloc: Test various special cases related to allocation failures

This test case exercises unusual code paths in allocation functions,
related to allocation failures.  Specifically, the test can reveal
the following bugs:

(a) calloc returns non-zero memory on fallback to sysmalloc.
(b) calloc can self-deadlock because it fails to release
    the arena lock on certain allocation failures.
(c) pvalloc can dereference a NULL arena pointer.

(a) and (b) appear specific to a faulty downstream backport.
(c) was fixed as part of commit 10ad46b.

The test for (a) was inspired by a reproducer supplied by Jeff Layton.

ChangeLog

@@ -1,3 +1,9 @@
+2015-12-29  Florian Weimer  <fweimer@redhat.com>
+
+	* malloc/tst-malloc-thread-fail.c: New file.
+	* malloc/Makefile (tests): Add tst-malloc-thread-fail.
+	(tst-malloc-thread-fail): Link against libpthread.
+
 2015-12-29  Mike Frysinger  <vapier@gentoo.org>
 
 	* scripts/list-fixed-bugs.py: Import argparse.  Call main instead.

malloc/Makefile

@@ -28,7 +28,8 @@ tests := mallocbug tst-malloc tst-valloc tst-calloc tst-obstack \
 	 tst-mallocstate tst-mcheck tst-mallocfork tst-trim1 \
 	 tst-malloc-usable tst-realloc tst-posix_memalign \
 	 tst-pvalloc tst-memalign tst-mallopt tst-scratch_buffer \
-	 tst-malloc-backtrace tst-malloc-thread-exit
+	 tst-malloc-backtrace tst-malloc-thread-exit \
+	 tst-malloc-thread-fail
 test-srcs = tst-mtrace
 
 routines = malloc morecore mcheck mtrace obstack \
@@ -49,6 +50,8 @@ $(objpfx)tst-malloc-backtrace: $(common-objpfx)nptl/libpthread.so \
 			       $(common-objpfx)nptl/libpthread_nonshared.a
 $(objpfx)tst-malloc-thread-exit: $(common-objpfx)nptl/libpthread.so \
 			       $(common-objpfx)nptl/libpthread_nonshared.a
+$(objpfx)tst-malloc-thread-fail: $(common-objpfx)nptl/libpthread.so \
+			       $(common-objpfx)nptl/libpthread_nonshared.a
 
 # These should be removed by `make clean'.
 extra-objs = mcheck-init.o libmcheck.a