malloc: Revert tcache double-free check (#1652495)

This commit is contained in:
Florian Weimer 2018-11-22 11:05:13 +01:00
parent 16caa0b760
commit 2f22666a8b
2 changed files with 225 additions and 1 deletions

220
glibc-rh1652495.patch Normal file
View File

@ -0,0 +1,220 @@
Revert "malloc: tcache double free check"
This reverts upstream commit bcdaad21d4635931d1bd3b54a7894276925d081d
because it causes this regression:
<https://bugzilla.redhat.com/show_bug.cgi?id=1652495>
diff --git a/dlfcn/dlerror.c b/dlfcn/dlerror.c
index 96bf92533335036b..33574faab65628ff 100644
--- a/dlfcn/dlerror.c
+++ b/dlfcn/dlerror.c
@@ -198,10 +198,7 @@ check_free (struct dl_action_result *rec)
Dl_info info;
if (_dl_addr (check_free, &info, &map, NULL) != 0 && map->l_ns == 0)
#endif
- {
- free ((char *) rec->errstring);
- rec->errstring = NULL;
- }
+ free ((char *) rec->errstring);
}
}
diff --git a/malloc/Makefile b/malloc/Makefile
index e6dfbfc14cb3d140..7d54bad866f63cb8 100644
--- a/malloc/Makefile
+++ b/malloc/Makefile
@@ -38,7 +38,6 @@ tests := mallocbug tst-malloc tst-valloc tst-calloc tst-obstack \
tst-malloc_info \
tst-malloc-too-large \
tst-malloc-stats-cancellation \
- tst-tcfree1 tst-tcfree2 \
tests-static := \
tst-interpose-static-nothread \
diff --git a/malloc/malloc.c b/malloc/malloc.c
index f730d7a2ee496d36..6d7a6a8cabb4edbf 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -2967,8 +2967,6 @@ mremap_chunk (mchunkptr p, size_t new_size)
typedef struct tcache_entry
{
struct tcache_entry *next;
- /* This field exists to detect double frees. */
- struct tcache_perthread_struct *key;
} tcache_entry;
/* There is one of these for each thread, which contains the
@@ -2992,11 +2990,6 @@ tcache_put (mchunkptr chunk, size_t tc_idx)
{
tcache_entry *e = (tcache_entry *) chunk2mem (chunk);
assert (tc_idx < TCACHE_MAX_BINS);
-
- /* Mark this chunk as "in the tcache" so the test in _int_free will
- detect a double free. */
- e->key = tcache;
-
e->next = tcache->entries[tc_idx];
tcache->entries[tc_idx] = e;
++(tcache->counts[tc_idx]);
@@ -3012,7 +3005,6 @@ tcache_get (size_t tc_idx)
assert (tcache->entries[tc_idx] > 0);
tcache->entries[tc_idx] = e->next;
--(tcache->counts[tc_idx]);
- e->key = NULL;
return (void *) e;
}
@@ -4226,26 +4218,6 @@ _int_free (mstate av, mchunkptr p, int have_lock)
{
size_t tc_idx = csize2tidx (size);
- /* Check to see if it's already in the tcache. */
- tcache_entry *e = (tcache_entry *) chunk2mem (p);
-
- /* This test succeeds on double free. However, we don't 100%
- trust it (it also matches random payload data at a 1 in
- 2^<size_t> chance), so verify it's not an unlikely coincidence
- before aborting. */
- if (__glibc_unlikely (e->key == tcache && tcache))
- {
- tcache_entry *tmp;
- LIBC_PROBE (memory_tcache_double_free, 2, e, tc_idx);
- for (tmp = tcache->entries[tc_idx];
- tmp;
- tmp = tmp->next)
- if (tmp == e)
- malloc_printerr ("free(): double free detected in tcache 2");
- /* If we get here, it was a coincidence. We've wasted a few
- cycles, but don't abort. */
- }
-
if (tcache
&& tc_idx < mp_.tcache_bins
&& tcache->counts[tc_idx] < mp_.tcache_count)
diff --git a/malloc/tst-tcfree1.c b/malloc/tst-tcfree1.c
deleted file mode 100644
index bc29375ce77304ac..0000000000000000
--- a/malloc/tst-tcfree1.c
+++ /dev/null
@@ -1,42 +0,0 @@
-/* Test that malloc tcache catches double free.
- Copyright (C) 2018 Free Software Foundation, Inc.
- This file is part of the GNU C Library.
-
- The GNU C Library is free software; you can redistribute it and/or
- modify it under the terms of the GNU Lesser General Public
- License as published by the Free Software Foundation; either
- version 2.1 of the License, or (at your option) any later version.
-
- The GNU C Library is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- Lesser General Public License for more details.
-
- You should have received a copy of the GNU Lesser General Public
- License along with the GNU C Library; if not, see
- <http://www.gnu.org/licenses/>. */
-
-#include <errno.h>
-#include <error.h>
-#include <limits.h>
-#include <malloc.h>
-#include <stdlib.h>
-#include <stdio.h>
-#include <sys/signal.h>
-
-static int
-do_test (void)
-{
- /* Do one allocation of any size that fits in tcache. */
- char * volatile x = malloc (32);
-
- free (x); // puts in tcache
- free (x); // should abort
-
- printf("FAIL: tcache double free not detected\n");
- return 1;
-}
-
-#define TEST_FUNCTION do_test
-#define EXPECTED_SIGNAL SIGABRT
-#include <support/test-driver.c>
diff --git a/malloc/tst-tcfree2.c b/malloc/tst-tcfree2.c
deleted file mode 100644
index 17f06bacd411c315..0000000000000000
--- a/malloc/tst-tcfree2.c
+++ /dev/null
@@ -1,48 +0,0 @@
-/* Test that malloc tcache catches double free.
- Copyright (C) 2018 Free Software Foundation, Inc.
- This file is part of the GNU C Library.
-
- The GNU C Library is free software; you can redistribute it and/or
- modify it under the terms of the GNU Lesser General Public
- License as published by the Free Software Foundation; either
- version 2.1 of the License, or (at your option) any later version.
-
- The GNU C Library is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- Lesser General Public License for more details.
-
- You should have received a copy of the GNU Lesser General Public
- License along with the GNU C Library; if not, see
- <http://www.gnu.org/licenses/>. */
-
-#include <errno.h>
-#include <error.h>
-#include <limits.h>
-#include <malloc.h>
-#include <stdlib.h>
-#include <stdio.h>
-#include <sys/signal.h>
-
-static int
-do_test (void)
-{
- char * volatile ptrs[20];
- int i;
-
- /* Allocate enough small chunks so that when we free them all, the tcache
- is full, and the first one we freed is at the end of its linked list. */
-#define COUNT 20
- for (i=0; i<COUNT; i++)
- ptrs[i] = malloc (20);
- for (i=0; i<COUNT; i++)
- free (ptrs[i]);
- free (ptrs[0]);
-
- printf("FAIL: tcache double free\n");
- return 1;
-}
-
-#define TEST_FUNCTION do_test
-#define EXPECTED_SIGNAL SIGABRT
-#include <support/test-driver.c>
diff --git a/manual/probes.texi b/manual/probes.texi
index 0ea560ed78bcfd7e..ab2a3102bb350ef4 100644
--- a/manual/probes.texi
+++ b/manual/probes.texi
@@ -243,18 +243,6 @@ This probe is triggered when the
value of this tunable.
@end deftp
-@deftp Probe memory_tcache_double_free (void *@var{$arg1}, int @var{$arg2})
-This probe is triggered when @code{free} determines that the memory
-being freed has probably already been freed, and resides in the
-per-thread cache. Note that there is an extremely unlikely chance
-that this probe will trigger due to random payload data remaining in
-the allocated memory matching the key used to detect double frees.
-This probe actually indicates that an expensive linear search of the
-tcache, looking for a double free, has happened. Argument @var{$arg1}
-is the memory location as passed to @code{free}, Argument @var{$arg2}
-is the tcache bin it resides in.
-@end deftp
-
@node Mathematical Function Probes
@section Mathematical Function Probes

View File

@ -1,6 +1,6 @@
%define glibcsrcdir glibc-2.28.9000-306-gbcdaad21d4
%define glibcversion 2.28.9000
%define glibcrelease 18%{?dist}
%define glibcrelease 19%{?dist}
# Pre-release tarballs are pulled in from git using a command that is
# effectively:
#
@ -158,6 +158,7 @@ Patch17: glibc-cs-path.patch
Patch18: glibc-c-utf8-locale.patch
Patch23: glibc-python3.patch
Patch28: glibc-rh1615608.patch
Patch29: glibc-rh1652495.patch
##############################################################################
# Continued list of core "glibc" package information:
@ -1899,6 +1900,9 @@ fi
%files -f compat-libpthread-nonshared.filelist -n compat-libpthread-nonshared
%changelog
* Thu Nov 22 2018 Florian Weimer <fweimer@redhat.com> - 2.28.9000-19
- malloc: Revert tcache double-free check (#1652495)
* Tue Nov 20 2018 DJ Delorie <dj@redhat.com> - 2.28.9000-18
- Auto-sync with upstream branch master,
commit bcdaad21d4635931d1bd3b54a7894276925d081d.