From 1e26d35193efbb29239c710a4c46a64708643320 Mon Sep 17 00:00:00 2001 From: Carlos O'Donell Date: Thu, 28 Sep 2017 11:05:18 -0600 Subject: malloc: Fix tcache leak after thread destruction [BZ #22111] The malloc tcache added in 2.26 will leak all of the elements remaining in the cache and the cache structure itself when a thread exits. The defect is that we do not set tcache_shutting_down early enough, and the thread simply recreates the tcache and places the elements back onto a new tcache which is subsequently lost as the thread exits (unfreed memory). The fix is relatively simple, move the setting of tcache_shutting_down earlier in tcache_thread_freeres. We add a test case which uses mallinfo and some heuristics to look for unaccounted for memory usage between the start and end of a thread start/join loop. It is very reliable at detecting that there is a leak given the number of iterations. Without the fix the test will consume 122MiB of leaked memory. --- malloc/Makefile | 3 +++ 1 file changed, 3 insertions(+) (limited to 'malloc/Makefile') diff --git a/malloc/Makefile b/malloc/Makefile index 50b487eeb5..6cf78e1177 100644 --- a/malloc/Makefile +++ b/malloc/Makefile @@ -34,6 +34,7 @@ tests := mallocbug tst-malloc tst-valloc tst-calloc tst-obstack \ tst-interpose-nothread \ tst-interpose-thread \ tst-alloc_buffer \ + tst-malloc-tcache-leak \ tests-static := \ tst-interpose-static-nothread \ @@ -242,3 +243,5 @@ tst-dynarray-fail-ENV = MALLOC_TRACE=$(objpfx)tst-dynarray-fail.mtrace $(objpfx)tst-dynarray-fail-mem.out: $(objpfx)tst-dynarray-fail.out $(common-objpfx)malloc/mtrace $(objpfx)tst-dynarray-fail.mtrace > $@; \ $(evaluate-test) + +$(objpfx)tst-malloc-tcache-leak: $(shared-thread-library) -- cgit 1.4.1