From:
Operating system: CentOS release 5.4
PHP version: 5.3.2
Package: Unknown/Other Function
Bug Type: Bug
Bug description:segv on zend_mm_search_large_block
Description:
------------
I create a extension to use my function written in C++ from PHP.
# I don't talk about the details of my extionsion because it is
proprietary.
configure parameters:
./configure --with-apxs2=/usr/local/apache2/bin/apxs \
--enable-sysvsem \
--enable-maintainer-zts \
--with-tsrm-pthreads
My extension is multi-threaded so PHP is the same.
When I pass hundreds of data to my extension, hundreds of threads are
created, and thousands of emallocs are called (though small size each).
# Physical memory = 256MB, Swap = 512MB
The first time I do it, it normally succeed.
But the second time, segmentation fault raised.
$ sudo gdb /usr/local/apache2/bin/httpd
(gdb) run -X -f /usr/local/apache2/conf/httpd.conf
---snip---
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x32ebb90 (LWP 5878)]
0x013b3d07 in zend_mm_search_large_block (heap=0x9a8cd70, true_size=16)
at /usr/local/src/php-5.3.2/Zend/zend_alloc.c:1792
1792 while ((p = p->child[p->child[0] != NULL])) {
(gdb) bt
#0 0x013b3d07 in zend_mm_search_large_block (heap=0x9a8cd70,
true_size=16)
at /usr/local/src/php-5.3.2/Zend/zend_alloc.c:1792
#1 0x013b3e34 in _zend_mm_alloc_int (heap=0x9a8cd70, size=1)
at /usr/local/src/php-5.3.2/Zend/zend_alloc.c:1852
#2 0x013b4d51 in _emalloc (size=1)
at /usr/local/src/php-5.3.2/Zend/zend_alloc.c:2340
#3 0x013b514f in _estrdup (s=0x706abf0 "")
at /usr/local/src/php-5.3.2/Zend/zend_alloc.c:2481
#4 0x06fb31ef in [snip] (arg=0x8cde23c)
at [snip]
#5 0x0098273b in start_thread () from /lib/libpthread.so.0
#6 0x00900cfe in clone () from /lib/libc.so.6
(gdb) p p
$1 = (zend_mm_free_block *) 0x0
(gdb) p *heap
$2 = {use_zend_alloc = 1, _malloc = 0, _free = 0, _realloc = 0,
free_bitmap = 0, large_free_bitmap = 131072, block_size = 262144,
compact_size = 2097152, segments_list = 0x9a8cfd0, storage = 0x9a8cd60,
real_size = 262144, real_peak = 262144, limit = 134217728, size = 10340,
peak = 10340, reserve_size = 8192, reserve = 0x9a8cfe0, overflow = 0,
internal = 0, cached = 76, cache = {0x0, 0x0, 0x9a8efe0, 0x0, 0x0, 0x0,
0x0,
0x0, 0x0, 0x9a8eff8, 0x0 <repeats 22 times>}, free_buckets =
{0x9a8ce38,
0x9a8ce38, 0x9a8ce40, 0x9a8ce40, 0x9a8ce48, 0x9a8ce48, 0x9a8ce50,
0x9a8ce50, 0x9a8ce58, 0x9a8ce58, 0x9a8ce60, 0x9a8ce60, 0x9a8ce68,
0x9a8ce68, 0x9a8ce70, 0x9a8ce70, 0x9a8ce78, 0x9a8ce78, 0x9a8ce80,
0x9a8ce80, 0x9a8ce88, 0x9a8ce88, 0x9a8ce90, 0x9a8ce90, 0x9a8ce98,
0x9a8ce98, 0x9a8cea0, 0x9a8cea0, 0x9a8cea8, 0x9a8cea8, 0x9a8ceb0,
0x9a8ceb0, 0x9a8ceb8, 0x9a8ceb8, 0x9a8cec0, 0x9a8cec0, 0x9a8cec8,
0x9a8cec8, 0x9a8ced0, 0x9a8ced0, 0x9a8ced8, 0x9a8ced8, 0x9a8cee0,
0x9a8cee0, 0x9a8cee8, 0x9a8cee8, 0x9a8cef0, 0x9a8cef0, 0x9a8cef8,
0x9a8cef8, 0x9a8cf00, 0x9a8cf00, 0x9a8cf08, 0x9a8cf08, 0x9a8cf10,
0x9a8cf10, 0x9a8cf18, 0x9a8cf18, 0x9a8cf20, 0x9a8cf20, 0x9a8cf28,
0x9a8cf28, 0x9a8cf30, 0x9a8cf30}, large_free_buckets = {
0x0 <repeats 32 times>}, rest_buckets = {0x9a8cfb8, 0x9a8cfb8}}
(gdb) p heap->large_free_buckets
$3 = {0x0 <repeats 32 times>}
I don't know this is the right way, but just add NULL check and nothing
happened.
$ git diff HEAD^
diff --git a/Zend/zend_alloc.c b/Zend/zend_alloc.c
index dac5454..707f75a 100644
--- a/Zend/zend_alloc.c
+++ b/Zend/zend_alloc.c
@@ -1789,6 +1789,7 @@ static zend_mm_free_block
*zend_mm_search_large_block(zend
/* Search for smallest "large" free block */
best_fit = p = heap->large_free_buckets[index +
zend_mm_low_bit(bitmap)]
+ if(!best_fit) return NULL;
while ((p = p->child[p->child[0] != NULL])) {
if (ZEND_MM_FREE_BLOCK_SIZE(p) <
ZEND_MM_FREE_BLOCK_SIZE(best_fi
best_fit = p;
--
Edit bug report at http://bugs.php.net/bug.php?id=51244&edit=1
--
Try a snapshot (PHP 5.2):
http://bugs.php.net/fix.php?id=51244&r=trysnapshot52
Try a snapshot (PHP 5.3):
http://bugs.php.net/fix.php?id=51244&r=trysnapshot53
Try a snapshot (PHP 6.0):
http://bugs.php.net/fix.php?id=51244&r=trysnapshot60
Fixed in SVN:
http://bugs.php.net/fix.php?id=51244&r=fixed
Fixed in SVN and need be documented:
http://bugs.php.net/fix.php?id=51244&r=needdocs
Fixed in release:
http://bugs.php.net/fix.php?id=51244&r=alreadyfixed
Need backtrace:
http://bugs.php.net/fix.php?id=51244&r=needtrace
Need Reproduce Script:
http://bugs.php.net/fix.php?id=51244&r=needscript
Try newer version:
http://bugs.php.net/fix.php?id=51244&r=oldversion
Not developer issue:
http://bugs.php.net/fix.php?id=51244&r=support
Expected behavior:
http://bugs.php.net/fix.php?id=51244&r=notwrong
Not enough info:
http://bugs.php.net/fix.php?id=51244&r=notenoughinfo
Submitted twice:
http://bugs.php.net/fix.php?id=51244&r=submittedtwice
register_globals:
http://bugs.php.net/fix.php?id=51244&r=globals
PHP 4 support discontinued: http://bugs.php.net/fix.php?id=51244&r=php4
Daylight Savings: http://bugs.php.net/fix.php?id=51244&r=dst
IIS Stability:
http://bugs.php.net/fix.php?id=51244&r=isapi
Install GNU Sed:
http://bugs.php.net/fix.php?id=51244&r=gnused
Floating point limitations:
http://bugs.php.net/fix.php?id=51244&r=float
No Zend Extensions:
http://bugs.php.net/fix.php?id=51244&r=nozend
MySQL Configuration Error:
http://bugs.php.net/fix.php?id=51244&r=mysqlcfg
