From e4e26210c3bdb5dcdce7a3def3b90fa45d3e2c89 Mon Sep 17 00:00:00 2001 From: Stefan Liebler Date: Tue, 21 Mar 2017 16:41:56 +0100 Subject: [PATCH] Fix failing test malloc/tst-interpose-nothread with GCC 7. The test malloc/tst-interpose-nothread fails on s390x if built with GCC 7 and glibc commit "Remove the str(n)dup inlines from string/bits/string2.h. Although inlining" (ae65d4f3c3995279ca458c460ebf8bab1885fa03) with output: error: free: 0x3fffdffa010: invalid allocation index: 0 (not less than 0) The destructor check_for_allocations in malloc/tst-interpose-aux.c is called twice. One time after the test-child-process has finished successfully and once after the test-parent-process finishes. During the latter invocation, allocation_index == 0. GCC 7 is now inlining the free function and calls unconditionally fail in get_header as header->allocation_index (type == size_t) is always >= allocation_index (= 0). Before the mentioned commit above, strdup was replaced by strlen, malloc and memcpy. The malloc call was also inlined and allocation_index was set to one. This patch moves the already existing compiler barrier before the invocation of free. ChangeLog: * malloc/tst-interpose-aux.c (check_for_allocations): Move compiler barrier before free. --- ChangeLog | 5 +++++ malloc/tst-interpose-aux.c | 2 +- 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/ChangeLog b/ChangeLog index eb5b25ae02..d8990ec5a0 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,8 @@ +2017-03-21 Stefan Liebler + + * malloc/tst-interpose-aux.c (check_for_allocations): + Move compiler barrier before free. + 2017-03-20 Joseph Myers [BZ #21279] diff --git a/malloc/tst-interpose-aux.c b/malloc/tst-interpose-aux.c index e80e979299..68282b41d5 100644 --- a/malloc/tst-interpose-aux.c +++ b/malloc/tst-interpose-aux.c @@ -113,11 +113,11 @@ check_for_allocations (void) { /* Make sure that malloc is called at least once from libc. */ void *volatile ptr = strdup ("ptr"); - free (ptr); /* Compiler barrier. The strdup function calls malloc, which updates allocation_index, but strdup is marked __THROW, so the compiler could optimize away the reload. */ __asm__ volatile ("" ::: "memory"); + free (ptr); /* If the allocation count is still zero, it means we did not interpose malloc successfully. */ if (allocation_index == 0)