Bug #71573 [Fbk]: Segfault (core dumped)

Edit report at https://bugs.php.net/bug.php?id=71573&edit=1 ID: 71573 Updated by: mbeccati@php.net Reported by: johan at x-tnd dot be Summary: Segfault (core dumped) Status: Feedback Type: Bug Package: PDO PgSQL Operating System: Linux CentoOS 7 PHP Version: 7.0.3 Assigned To: mbeccati Block user comment: N Private report: N New Comment: Thanks for your help. Nice investigation work. I would try next to set a gdb breakpoint after the connection is initialised, then a watchpoint to see when the connection data is overwritten. Previous Comments: ------------------------------------------------------------------------ [2016-04-01 09:44:19] phofstetter at sensational dot ch now using a rebuilt non-stripped libpq, I started investigating the stack frames a bit more and it definitely looks like the connection object libpq is working on at this point is corrupt: (gdb) frame 0 #0 0x00007f250d6e2883 in pqGetc (result=0x7ffe6ad53527 "", conn=0x7f250e6ac498) at /home/crazyhat/postgresql-9.4-9.4.6/build/../src/interfaces/libpq/fe-misc.c:104 104 *result = conn->inBuffer[conn->inCursor++]; (gdb) p conn->pghost $7 = 0x7f250e6ac818 "\340\307j\016%\177" (gdb) p conn->dbName $8 = 0x0 (gdb) p conn->last_query $9 = 0x7f250e7fcab8 "\230\304\177\016%\177" (gdb) p conn->errorMessage $10 = {data = 0x7f250e6c4908 "\200<`\016%\177", len = 4294967297, maxlen = 16} (gdb) this doesn't look very... correct 😊 Also, that connection doesn't get corrupted inside of libpq - on frame 5 (the last one inside PHP), stuff already looks wahoonie-shaped: (gdb) frame 5 #5 0x00007f250d6dfe0b in PQexec (conn=0x7f250e6ac498, query=0x7f250e730730 "DEALLOCATE pdo_stmt_00000015") at /home/crazyhat/postgresql-9.4-9.4.6/build/../src/interfaces/libpq/fe-exec.c:1826 1826 if (!PQexecStart(conn)) (gdb) p conn->last_query $12 = 0x7f250e7fcab8 "\230\304\177\016%\177" (gdb) p conn $13 = (PGconn *) 0x7f250e6ac498 I'm not too well-versed with valgrind - can you give me some further hints in how I can get more information out of valgrind or with gdb? ------------------------------------------------------------------------ [2016-04-01 09:30:44] phofstetter at sensational dot ch I have great trouble making a reduced test-case: While the crash is 100% reproducible with a specific request, I'm unsucessful in reducing the testcase, mainly because a lot of things are going on in the request in question. I'll need a bit more time. In the mean time, I have run fpm in valgind, where I had to add a ton of error suppresions because of issues in OpenSSL (the request in question is validating a signature). The errors were 1000s of either - Conditional jump or move depends on uninitialised value(s) - Use of uninitialised value of size 8 all of them happening in libcrypto. Once that's cleaned up, here's the valgrind output of the crash. Yes, this might look like an issue in libpq (especially as the values passed into PQexec look sensible), but I still suspect PHP as this doesn't happen in 5.6 and I have not seen this crash happen in libpq before. This is php-7.0.4 (self compiled) and libpq-9.4 (from Debian 8: libpq5_9.4.6-0+deb8u1) ==24783== Memcheck, a memory error detector ==24783== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al. ==24783== Using Valgrind-3.10.0 and LibVEX; rerun with -h for copyright info ==24783== Command: /opt/php/7.0/sbin/php-fpm --fpm-config /opt/php/7.0/etc/php-fpm.conf -F ==24783== ==24783== Warning: set address range perms: large range [0x14b6f000, 0x2cb6f000) (defined) [01-Apr-2016 11:24:24] NOTICE: fpm is running, pid 24783 [01-Apr-2016 11:24:24] NOTICE: ready to handle connections ==24784== Invalid write of size 1 ==24784== at 0xEB1F2E8: resetPQExpBuffer (pqexpbuffer.c:154) ==24784== by 0xEB1025E: PQsendQueryStart (fe-exec.c:1351) ==24784== by 0xEB0FC59: PQsendQuery (fe-exec.c:1114) ==24784== by 0xEB10E28: PQexec (fe-exec.c:1828) ==24784== by 0xE8F7352: pgsql_stmt_dtor (pgsql_statement.c:64) ==24784== by 0x5D1B79: php_pdo_free_statement (pdo_stmt.c:2316) ==24784== by 0x7A2EE1: zend_objects_store_del (zend_objects_API.c:182) ==24784== by 0x77A13E: i_zval_ptr_dtor (zend_variables.h:58) ==24784== by 0x77A13E: zend_array_destroy (zend_hash.c:1322) ==24784== by 0x7684E8: i_zval_ptr_dtor (zend_variables.h:58) ==24784== by 0x7684E8: _zval_dtor_func_for_ptr (zend_variables.c:122) ==24784== by 0x77A207: i_zval_ptr_dtor (zend_variables.h:58) ==24784== by 0x77A207: zend_array_destroy (zend_hash.c:1326) ==24784== by 0x79E20A: i_zval_ptr_dtor (zend_variables.h:58) ==24784== by 0x79E20A: zend_object_std_dtor (zend_objects.c:69) ==24784== by 0x7A2BB0: zend_objects_store_free_object_storage (zend_objects_API.c:103) ==24784== Address 0x0 is not stack'd, malloc'd or (recently) free'd ==24784== ==24784== ==24784== Process terminating with default action of signal 11 (SIGSEGV) ==24784== Access not within mapped region at address 0x0 ==24784== at 0xEB1F2E8: resetPQExpBuffer (pqexpbuffer.c:154) ==24784== by 0xEB1025E: PQsendQueryStart (fe-exec.c:1351) ==24784== by 0xEB0FC59: PQsendQuery (fe-exec.c:1114) ==24784== by 0xEB10E28: PQexec (fe-exec.c:1828) ==24784== by 0xE8F7352: pgsql_stmt_dtor (pgsql_statement.c:64) ==24784== by 0x5D1B79: php_pdo_free_statement (pdo_stmt.c:2316) ==24784== by 0x7A2EE1: zend_objects_store_del (zend_objects_API.c:182) ==24784== by 0x77A13E: i_zval_ptr_dtor (zend_variables.h:58) ==24784== by 0x77A13E: zend_array_destroy (zend_hash.c:1322) ==24784== by 0x7684E8: i_zval_ptr_dtor (zend_variables.h:58) ==24784== by 0x7684E8: _zval_dtor_func_for_ptr (zend_variables.c:122) ==24784== by 0x77A207: i_zval_ptr_dtor (zend_variables.h:58) ==24784== by 0x77A207: zend_array_destroy (zend_hash.c:1326) ==24784== by 0x79E20A: i_zval_ptr_dtor (zend_variables.h:58) ==24784== by 0x79E20A: zend_object_std_dtor (zend_objects.c:69) ==24784== by 0x7A2BB0: zend_objects_store_free_object_storage (zend_objects_API.c:103) ==24784== If you believe this happened as a result of a stack ==24784== overflow in your program's main thread (unlikely but ==24784== possible), you can try to increase the size of the ==24784== main thread stack using the --main-stacksize= flag. ==24784== The main thread stack size used in this run was 8388608. ==24784== ==24784== HEAP SUMMARY: ==24784== in use at exit: 4,150,545 bytes in 33,595 blocks ==24784== total heap usage: 70,756 allocs, 37,161 frees, 13,929,319 bytes allocated ==24784== ==24784== LEAK SUMMARY: ==24784== definitely lost: 208 bytes in 1 blocks ==24784== indirectly lost: 670 bytes in 25 blocks ==24784== possibly lost: 3,054,043 bytes in 27,263 blocks ==24784== still reachable: 1,095,624 bytes in 6,306 blocks ==24784== suppressed: 0 bytes in 0 blocks ==24784== Rerun with --leak-check=full to see details of leaked memory ==24784== ==24784== For counts of detected and suppressed errors, rerun with: -v ==24784== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 175536 from 2710) ==24784== could not unlink /tmp/vgdb-pipe-from-vgdb-to-24784-by-???-on-??? ==24784== could not unlink /tmp/vgdb-pipe-to-vgdb-from-24784-by-???-on-??? ==24784== could not unlink /tmp/vgdb-pipe-shared-mem-vgdb-24784-by-???-on-??? [01-Apr-2016 11:24:39] WARNING: [pool www] child 24784 exited on signal 11 (SIGSEGV) after 15.036450 seconds from start [01-Apr-2016 11:24:39] NOTICE: [pool www] child 25243 started ------------------------------------------------------------------------ [2016-04-01 07:36:53] mbeccati@php.net Thanks. Waiting for more feedback. ------------------------------------------------------------------------ [2016-04-01 07:33:35] phofstetter at sensational dot ch I'm also seeing this on Debian Jessie with PHP 7.0.4. I'll try to make a reduced testcase somehow. ------------------------------------------------------------------------ [2016-02-18 08:35:32] mbeccati@php.net Could you please try running the script using valgrind? It will be much slower, but it might give us a better idea of what's causing the issue. ------------------------------------------------------------------------ The remainder of the comments for this report are too long. 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