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libpcre2-8-0 10.44 SIGSEGV segfault crash with PHP 8.1.29 #435

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archon810 opened this issue Aug 1, 2024 · 6 comments
Open

libpcre2-8-0 10.44 SIGSEGV segfault crash with PHP 8.1.29 #435

archon810 opened this issue Aug 1, 2024 · 6 comments

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@archon810
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archon810 commented Aug 1, 2024 •
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Hi,

We recently updated to OpenSUSE 15.6 (from 15.4) and are testing an update from PHP 8.0 to 8.1 (8.1.29 currently). On the test machine where we're testing, all of a sudden I'm seeing constant PHP8 crashes. After using gdb to see what's going on, they all seem to point to libpcre2-8-0, specifically pcre2_jit_match_8, php_pcre_replace_impl, php_pcre_replace, and php_replace_in_subject.

As has been suggested in other places like #57, oerdnj/deb.sury.org#1721, https://bugs.php.net/bug.php?id=81647, it seems like JIT is the culprit once again (the only other recent PHP crashes I've observed were related to opcache.jit being enabled).

Here's a sample backtrace from one such crash.

gdb php8 core.php.3000.pylon.1722366712
GNU gdb (GDB; devel:gcc) 14.2
...
Reading symbols from php8...
Reading symbols from /usr/lib/debug/usr/bin/php-8.1.29-lp156.2.1.x86_64.debug...
warning: Can't open file /var/run/nscd/dbUKm9bO (deleted) during file-backed mapping note processing
warning: Can't open file /usr/lib64/libltdl.so.7.3.1 (deleted) during file-backed mapping note processing
warning: Can't open file /usr/lib64/libhogweed.so.6.9 (deleted) during file-backed mapping note processing
warning: Can't open file /usr/lib64/libnettle.so.8.9 (deleted) during file-backed mapping note processing
warning: Can't open file /usr/lib64/libcurl.so.4.8.0 (deleted) during file-backed mapping note processing
warning: Can't open file /usr/lib64/libpcre2-8.so.0.12.0 (deleted) during file-backed mapping note processing
[New LWP 3000]
warning: .dynamic section for "/usr/lib64/libpcre2-8.so.0" is not at the expected address (wrong library or version mismatch?)
warning: .dynamic section for "/usr/lib64/libcurl.so.4" is not at the expected address (wrong library or version mismatch?)
warning: .dynamic section for "/usr/lib64/libxcb.so.1" is not at the expected address (wrong library or version mismatch?)
warning: .dynamic section for "/usr/lib64/libonig.so.4" is not at the expected address (wrong library or version mismatch?)
Missing separate debuginfo for /usr/lib64/libicuio.so.73.
The debuginfo package for this file is probably broken.
bMissing separate debuginfo for /usr/lib64/libicui18n.so.73.
The debuginfo package for this file is probably broken.
Missing separate debuginfo for /usr/lib64/libicuuc.so.73.
The debuginfo package for this file is probably broken.
Missing separate debuginfo for /usr/lib64/libicudata.so.73.
The debuginfo package for this file is probably broken.
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".

Core was generated by `/usr/bin/php <SNIPPED BY archon810>'.
Program terminated with signal SIGSEGV, Segmentation fault.

#0  0x000073d0084ecfc5 in pcre2_jit_match_8 (code=0x5bfa81d18570, subject=subject@entry=0x73cffd616d60 "SELECT 1", length=length@entry=8, start_offset=start_offset@entry=0, options=0, options@entry=1073741824, match_data=match_data@entry=0x5bfa81db53c0, mcontext=0x5bfa81db5350) at src/pcre2_jit_match.c:142
142       arguments.offset_limit = mcontext->offset_limit;
Missing separate debuginfos, use: zypper install glibc-debuginfo-2.38-150600.14.5.1.x86_64 libcom_err2-debuginfo-1.47.0-150600.4.3.2.x86_64 libgcc_s1-debuginfo-13.3.0+git8781-150000.1.12.1.x86_64 libgcrypt20-debuginfo-1.10.3-150600.1.23.x86_64 libglib-2_0-0-debuginfo-2.78.6-150600.4.3.1.x86_64 libgpg-error0-debu
ginfo-1.47-150600.1.3.x86_64 libjitterentropy3-debuginfo-3.4.1-150000.1.12.1.x86_64 libltdl7-debuginfo-2.4.6-150000.3.8.1.x86_64 libmemcachedprotocol0-debuginfo-1.1.4-150600.2.2.x86_64 libmemcachedutil2-debuginfo-1.1.4-150600.2.2.x86_64 libonig4-debuginfo-6.7.0-150000.3.6.1.x86_64 libopenssl3-debuginfo-3.1.4-150
600.5.10.1.x86_64 libsodium23-debuginfo-1.0.18-150000.4.6.1.x86_64 libssh4-debuginfo-0.10.6-lp156.95.1.x86_64 libtiff5-debuginfo-4.0.9-150000.45.41.1.x86_64 libwebp7-debuginfo-1.0.3-150200.3.10.1.x86_64 libxcb1-debuginfo-1.13-150000.3.11.1.x86_64 libxml2-2-debuginfo-2.10.3-150500.5.17.1.x86_64 libxslt1-debuginfo
-1.1.39-lp156.146.1.x86_64 libzip5-debuginfo-1.10.1-150600.1.5.x86_64 php8-gd-debuginfo-8.1.29-lp156.2.1.x86_64 php8-intl-debuginfo-8.1.29-lp156.2.1.x86_64 php8-openssl-debuginfo-8.1.29-lp156.2.1.x86_64 php8-sockets-debuginfo-8.1.29-lp156.2.1.x86_64 php8-tokenizer-debuginfo-8.1.29-lp156.2.1.x86_64
(gdb) bt
#0  0x000073d0084ecfc5 in pcre2_jit_match_8 (code=0x5bfa81d18570, subject=subject@entry=0x73cffd616d60 "SELECT 1", length=length@entry=8, start_offset=start_offset@entry=0, options=0, options@entry=1073741824, match_data=match_data@entry=0x5bfa81db53c0, mcontext=0x5bfa81db5350) at src/pcre2_jit_match.c:142
#1  0x00005bfa816557b2 in php_pcre_replace_impl (pce=pce@entry=0x73cfff7b2040, subject_str=subject_str@entry=0x73cffd616d48, subject=subject@entry=0x73cffd616d60 "SELECT 1", subject_len=subject_len@entry=8, replace_str=replace_str@entry=0x73cfff97f360, limit=limit@entry=18446744073709551615,
    replace_count=0x7ffcac255208) at /usr/src/debug/php8-8.1.29-lp156.2.1.x86_64/ext/pcre/php_pcre.c:1664
#2  0x00005bfa816560ce in php_pcre_replace (regex=<optimized out>, subject_str=0x73cffd616d48, subject=0x73cffd616d60 "SELECT 1", subject_len=8, replace_str=0x73cfff97f360, limit=18446744073709551615, replace_count=0x7ffcac255208) at /usr/src/debug/php8-8.1.29-lp156.2.1.x86_64/ext/pcre/php_pcre.c:1606
#3  0x00005bfa81656acd in php_replace_in_subject (replace_count=0x7ffcac255208, limit=<optimized out>, subject=<optimized out>, replace_ht=0x0, replace_str=<optimized out>, regex_ht=<optimized out>, regex_str=<optimized out>) at /usr/src/debug/php8-8.1.29-lp156.2.1.x86_64/ext/pcre/php_pcre.c:2176
#4  preg_replace_common (is_filter=false, return_value=0x73cfe548d040, execute_data=0x73cfe548d110) at /usr/src/debug/php8-8.1.29-lp156.2.1.x86_64/ext/pcre/php_pcre.c:2314
#5  zif_preg_replace (execute_data=0x73cfe548d110, return_value=0x73cfe548d040) at /usr/src/debug/php8-8.1.29-lp156.2.1.x86_64/ext/pcre/php_pcre.c:2371
#6  0x000073d007de303d in xdebug_execute_internal (current_execute_data=0x73cfe548d110, return_value=0x73cfe548d040) at /tmp/pear/temp/xdebug/src/base/base.c:1024
#7  0x00005bfa816164ae in ZEND_DO_FCALL_SPEC_OBSERVER_HANDLER () at /usr/src/debug/php8-8.1.29-lp156.2.1.x86_64/Zend/zend_vm_execute.h:1981
#8  0x00005bfa8187760c in execute_ex (ex=0x5bfa82118800) at /usr/src/debug/php8-8.1.29-lp156.2.1.x86_64/Zend/zend_vm_execute.h:55852
#9  0x00005bfa81616419 in ZEND_DO_FCALL_SPEC_OBSERVER_HANDLER () at /usr/src/debug/php8-8.1.29-lp156.2.1.x86_64/Zend/zend_vm_execute.h:1946
#10 0x00005bfa8187760c in execute_ex (ex=0x5bfa82118800) at /usr/src/debug/php8-8.1.29-lp156.2.1.x86_64/Zend/zend_vm_execute.h:55852
#11 0x00005bfa81616419 in ZEND_DO_FCALL_SPEC_OBSERVER_HANDLER () at /usr/src/debug/php8-8.1.29-lp156.2.1.x86_64/Zend/zend_vm_execute.h:1946
#12 0x00005bfa8187760c in execute_ex (ex=0x5bfa82118800) at /usr/src/debug/php8-8.1.29-lp156.2.1.x86_64/Zend/zend_vm_execute.h:55852
#13 0x00005bfa81616419 in ZEND_DO_FCALL_SPEC_OBSERVER_HANDLER () at /usr/src/debug/php8-8.1.29-lp156.2.1.x86_64/Zend/zend_vm_execute.h:1946
#14 0x00005bfa8187760c in execute_ex (ex=0x5bfa82118800) at /usr/src/debug/php8-8.1.29-lp156.2.1.x86_64/Zend/zend_vm_execute.h:55852
#15 0x00005bfa81616419 in ZEND_DO_FCALL_SPEC_OBSERVER_HANDLER () at /usr/src/debug/php8-8.1.29-lp156.2.1.x86_64/Zend/zend_vm_execute.h:1946
#16 0x00005bfa8187760c in execute_ex (ex=0x5bfa82118800) at /usr/src/debug/php8-8.1.29-lp156.2.1.x86_64/Zend/zend_vm_execute.h:55852
#17 0x00005bfa81616419 in ZEND_DO_FCALL_SPEC_OBSERVER_HANDLER () at /usr/src/debug/php8-8.1.29-lp156.2.1.x86_64/Zend/zend_vm_execute.h:1946
#18 0x00005bfa8187760c in execute_ex (ex=0x5bfa82118800) at /usr/src/debug/php8-8.1.29-lp156.2.1.x86_64/Zend/zend_vm_execute.h:55852
#19 0x00005bfa81616419 in ZEND_DO_FCALL_SPEC_OBSERVER_HANDLER () at /usr/src/debug/php8-8.1.29-lp156.2.1.x86_64/Zend/zend_vm_execute.h:1946
#20 0x00005bfa8187760c in execute_ex (ex=0x5bfa82118800) at /usr/src/debug/php8-8.1.29-lp156.2.1.x86_64/Zend/zend_vm_execute.h:55852
...
this repeats for tens of thousands of lines - probably an endless loop

As you can see, it looks like the query was just SELECT 1 and whatever regex was used to parse it crashes the whole PHP.

I think in our code (using Wordpress), it happens here:

            //Specify a dummy query
            if ( $wpdb->db_connect( 'SELECT 1' ) ) {
                error_reporting( $error_reporting );

                $no_database = false;
                break;
            }

From what I can tell based on the messages in /var/log/messages, the pcre library loaded is libpcre2-8.so.0.13.0, which according to the package manager is version 10.44 (the latest available).

2024-08-01T11:02:55.361543-07:00 pylon kernel: [3516751.265471] php[19527]: segfault at 7fff87da0f98 ip 0000622dafa528ad sp 00007fff87da0fa0 error 6 in php[622daf600000+7cf000] likely on CPU 1 (core 1, socket 0)
2024-08-01T11:02:57.324535-07:00 pylon kernel: [3516753.226213] php[19707]: segfault at 7ffcf0b1cff8 ip 00007169714d1fe9 sp 00007ffcf0b1d000 error 6 in libpcre2-8.so.0.13.0[71697146e000+bf000] likely on CPU 5 (core 5, socket 0)
2024-08-01T11:02:58.622204-07:00 pylon kernel: [3516754.517316] php[19534]: segfault at 7ffca2843fe8 ip 0000792ef127f422 sp 00007ffca2843fb0 error 6 likely on CPU 2 (core 2, socket 0)
2024-08-01T11:02:59.577390-07:00 pylon kernel: [3516755.481372] php[19614]: segfault at 7ffdc5062ff0 ip 00007b13d6ed8068 sp 00007ffdc5062fd0 error 6 likely on CPU 1 (core 1, socket 0)
2024-08-01T11:03:04.225560-07:00 pylon kernel: [3516760.127703] php[19524]: segfault at 7ffd6454ffd8 ip 00007d8ab5673f12 sp 00007ffd6454ffa0 error 6 likely on CPU 1 (core 1, socket 0)
2024-08-01T11:03:07.152392-07:00 pylon kernel: [3516763.054547] php[19706]: segfault at 7ffd871d6fe0 ip 000079beaa22c068 sp 00007ffd871d6fc0 error 6 likely on CPU 2 (core 2, socket 0)
2024-08-01T11:03:08.288678-07:00 pylon kernel: [3516764.192171] php[19705]: segfault at 7ffdc1141ff8 ip 0000799f3c373fe9 sp 00007ffdc1142000 error 6 in libpcre2-8.so.0.13.0[799f3c310000+bf000] likely on CPU 5 (core 5, socket 0)
2024-08-01T11:03:09.114457-07:00 pylon kernel: [3516765.016904] php[19523]: segfault at 7fff5910afd8 ip 00007587ea441fdf sp 00007fff5910afa0 error 6 likely on CPU 4 (core 4, socket 0)
2024-08-01T11:03:14.294606-07:00 pylon kernel: [3516770.197875] php[19532]: segfault at 7ffeccc46fd8 ip 000063fb26c528ad sp 00007ffeccc46fe0 error 6 in php[63fb26800000+7cf000] likely on CPU 5 (core 5, socket 0)
2024-08-01T11:03:20.843902-07:00 pylon kernel: [3516776.745451] php[19525]: segfault at 7ffc3ae71fe8 ip 00007a2cb72c2fdf sp 00007ffc3ae71fb0 error 6 likely on CPU 2 (core 2, socket 0)
2024-08-01T11:03:24.383890-07:00 pylon kernel: [3516780.285203] php[19533]: segfault at 7ffdfb842fe8 ip 000079fb5177dfdf sp 00007ffdfb842fb0 error 6 likely on CPU 2 (core 2, socket 0)
2024-08-01T11:03:27.010622-07:00 pylon kernel: [3516782.913697] php[19704]: segfault at 7fff0dff3ff8 ip 00007d753d687fe9 sp 00007fff0dff4000 error 6 in libpcre2-8.so.0.13.0[7d753d624000+bf000] likely on CPU 4 (core 4, socket 0)

zypper info libpcre2-8-0
Loading repository data...
Reading installed packages...


Information for package libpcre2-8-0:
-------------------------------------
Repository     : openSUSE BuildService - devel:libraries:c_c++
Name           : libpcre2-8-0
Version        : 10.44-lp156.80.1
Arch           : x86_64
Vendor         : obs://build.opensuse.org/devel:libraries:c_c++
Installed Size : 973.4 KiB
Installed      : Yes (automatically)
Status         : up-to-date
Source package : pcre2-10.44-lp156.80.1.src
Upstream URL   : https://www.pcre.org
Summary        : A library for Perl-compatible regular expressions
Description    : 
    The PCRE2 library is a set of functions that implement regular
    expression pattern matching using the same syntax and semantics
    as Perl 5.

    PCRE2 is a re-working of the original PCRE library to provide an entirely new
    API.

    This PCRE2 library variant supports 8-bit and UTF-8 strings.
    (See also libpcre2-16 and libpcre2-32)

Any ideas?
@archon810 archon810 changed the title libpcre2-8-0 10.44 SIGSEGV segfault crash with PHP 8.1.29 and a seemingly very simple regex libpcre2-8-0 10.44 SIGSEGV segfault crash with PHP 8.1.29 Aug 1, 2024
@archon810
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Hmm, I disabled pcre.jit, but it's still crashing and still using a function name that mentions jit.

Here's how it's set in both /etc/php8/apache/php.ini and /etc/php8/cli/php.ini:

pcre.jit=0

I verified that the value is set correctly:

php8 -r 'echo phpinfo();'|ack pcre.jit
pcre.jit => 0 => 0

#0  0x000079f9bee41fcd in ?? ()
#1  0x0000000000000008 in ?? ()
#2  0x00005c00f3889570 in ?? ()
#3  0x00005c00f39263c0 in ?? ()
#4  0x000079f9c12b9fec in pcre2_jit_match_8 (code=0x5c00f3889570, subject=subject@entry=0x79f9b6ec1310 "SELECT 1", length=length@entry=8, start_offset=start_offset@entry=0, options=options@entry=1073741824, match_data=match_data@entry=0x5c00f39263c0, mcontext=0x5c00f3926350) at src/pcre2_jit_match.c:171
#5  0x00005c00f18557b2 in php_pcre_replace_impl (pce=pce@entry=0x79f9b9187a80, subject_str=subject_str@entry=0x79f9b6ec12f8, subject=subject@entry=0x79f9b6ec1310 "SELECT 1", subject_len=subject_len@entry=8, replace_str=replace_str@entry=0x79f9b91963c0, limit=limit@entry=18446744073709551615,
    replace_count=0x7ffe7b888258) at /usr/src/debug/php8-8.1.29-lp156.2.1.x86_64/ext/pcre/php_pcre.c:1664
#6  0x00005c00f18560ce in php_pcre_replace (regex=<optimized out>, subject_str=0x79f9b6ec12f8, subject=0x79f9b6ec1310 "SELECT 1", subject_len=8, replace_str=0x79f9b91963c0, limit=18446744073709551615, replace_count=0x7ffe7b888258) at /usr/src/debug/php8-8.1.29-lp156.2.1.x86_64/ext/pcre/php_pcre.c:1606
#7  0x00005c00f1856acd in php_replace_in_subject (replace_count=0x7ffe7b888258, limit=<optimized out>, subject=<optimized out>, replace_ht=0x0, replace_str=<optimized out>, regex_ht=<optimized out>, regex_str=<optimized out>) at /usr/src/debug/php8-8.1.29-lp156.2.1.x86_64/ext/pcre/php_pcre.c:2176
#8  preg_replace_common (is_filter=false, return_value=0x79f99d237380, execute_data=0x79f99d237450) at /usr/src/debug/php8-8.1.29-lp156.2.1.x86_64/ext/pcre/php_pcre.c:2314
#9  zif_preg_replace (execute_data=0x79f99d237450, return_value=0x79f99d237380) at /usr/src/debug/php8-8.1.29-lp156.2.1.x86_64/ext/pcre/php_pcre.c:2371
#10 0x000079f9c0b9403d in xdebug_execute_internal (current_execute_data=0x79f99d237450, return_value=0x79f99d237380) at /tmp/pear/temp/xdebug/src/base/base.c:1024
#11 0x00005c00f18164ae in ZEND_DO_FCALL_SPEC_OBSERVER_HANDLER () at /usr/src/debug/php8-8.1.29-lp156.2.1.x86_64/Zend/zend_vm_execute.h:1981
#12 0x00005c00f1a7760c in execute_ex (ex=0x7ffe7b888030) at /usr/src/debug/php8-8.1.29-lp156.2.1.x86_64/Zend/zend_vm_execute.h:55852
#13 0x00005c00f1816419 in ZEND_DO_FCALL_SPEC_OBSERVER_HANDLER () at /usr/src/debug/php8-8.1.29-lp156.2.1.x86_64/Zend/zend_vm_execute.h:1946
#14 0x00005c00f1a7760c in execute_ex (ex=0x7ffe7b888030) at /usr/src/debug/php8-8.1.29-lp156.2.1.x86_64/Zend/zend_vm_execute.h:55852

@archon810 archon810 mentioned this issue Aug 1, 2024
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@zherczeg
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zherczeg commented Aug 2, 2024

According to your report, this line cause the issue:
arguments.offset_limit = mcontext->offset_limit;

This is simply a value reading and setting a stack allocated variable.
https://github.com/PCRE2Project/pcre2/blob/master/src/pcre2_jit_match.c#L142C1-L142C51

Either mcontext=0x5bfa81db5350 is not a valid pointer, or stack limit is reached. Could you check with gdb that mcontext pointer is valid (it will complain if mcontext->offset_limit is not readable) and also check you still have enough stack?

The second case is strange as well, since it does run jit when you disabled it. Anyway, it looks like it runs the jit code. Please disassemble the code with disassemble $pc-32, $pc+32 with gdb. The kernel might prevent executing jit code or we have another pointer issue.

@archon810
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@zherczeg Sorry for the late reply.

I just tried this with the latest core:

(gdb) print mcontext->offset_limit
$2 = 18446744073709551615

As for checking whether I have enough stack, could you please provide more details? I did su'ed to the user that owns the process (wwwrun) and did ulimit -a which showed stack size (kbytes, -s) 8192. This is probably a standard value, how do we know if it's not enough?

(gdb) disassemble $pc-32, $pc+32
Dump of assembler code from 0x73de352714ca to 0x73de3527150a:
   0x000073de352714ca <pcre2_match_8+10>:       mov    %r8d,%ebx
   0x000073de352714cd <pcre2_match_8+13>:       sub    $0x2c8,%rsp
   0x000073de352714d4 <pcre2_match_8+20>:       mov    %fs:0x28,%rax
   0x000073de352714dd <pcre2_match_8+29>:       mov    %rax,0x2b8(%rsp)
   0x000073de352714e5 <pcre2_match_8+37>:       xor    %eax,%eax
   0x000073de352714e7 <pcre2_match_8+39>:       test   %rsi,%rsi
=> 0x000073de352714ea <pcre2_match_8+42>:       mov    %rdi,0x28(%rsp)
   0x000073de352714ef <pcre2_match_8+47>:       mov    %rsi,0x18(%rsp)
   0x000073de352714f4 <pcre2_match_8+52>:       mov    %rdx,0x30(%rsp)
   0x000073de352714f9 <pcre2_match_8+57>:       mov    %rcx,0x70(%rsp)
   0x000073de352714fe <pcre2_match_8+62>:       mov    %r9,0x8(%rsp)
   0x000073de35271503 <pcre2_match_8+67>:       mov    0x300(%rsp),%rbp
End of assembler dump.

Just to be clear, the above is all using this latest dump from a couple of days ago:

(gdb) bt
#0  pcre2_match_8 (code=0x5b7fcbe2dfa0, subject=subject@entry=0x73de2ae9a928 "SELECT 1", length=length@entry=8, start_offset=start_offset@entry=0, options=1073741824, match_data=match_data@entry=0x5b7fcbecabf0, mcontext=0x5b7fcbecab80) at src/pcre2_match.c:6533
#1  0x00005b7fcac55b0e in php_pcre_replace_impl (pce=pce@entry=0x73de2d15dd40, subject_str=subject_str@entry=0x73de2ae9a910, subject=subject@entry=0x73de2ae9a928 "SELECT 1", subject_len=subject_len@entry=8, replace_str=replace_str@entry=0x73de2d16b320, limit=limit@entry=18446744073709551615,
    replace_count=0x7ffe6d1082d8) at /usr/src/debug/php8-8.1.29-lp156.3.2.x86_64/ext/pcre/php_pcre.c:1668
#2  0x00005b7fcac560ce in php_pcre_replace (regex=<optimized out>, subject_str=0x73de2ae9a910, subject=0x73de2ae9a928 "SELECT 1", subject_len=8, replace_str=0x73de2d16b320, limit=18446744073709551615, replace_count=0x7ffe6d1082d8) at /usr/src/debug/php8-8.1.29-lp156.3.2.x86_64/ext/pcre/php_pcre.c:1606
#3  0x00005b7fcac56acd in php_replace_in_subject (replace_count=0x7ffe6d1082d8, limit=<optimized out>, subject=<optimized out>, replace_ht=0x0, replace_str=<optimized out>, regex_ht=<optimized out>, regex_str=<optimized out>) at /usr/src/debug/php8-8.1.29-lp156.3.2.x86_64/ext/pcre/php_pcre.c:2176
#4  preg_replace_common (is_filter=false, return_value=0x73de1983e040, execute_data=0x73de1983e110) at /usr/src/debug/php8-8.1.29-lp156.3.2.x86_64/ext/pcre/php_pcre.c:2314
#5  zif_preg_replace (execute_data=0x73de1983e110, return_value=0x73de1983e040) at /usr/src/debug/php8-8.1.29-lp156.3.2.x86_64/ext/pcre/php_pcre.c:2371
#6  0x000073de3509f03d in xdebug_execute_internal (current_execute_data=0x73de1983e110, return_value=0x73de1983e040) at /tmp/pear/temp/xdebug/src/base/base.c:1024
#7  0x00005b7fcac164ae in ZEND_DO_FCALL_SPEC_OBSERVER_HANDLER () at /usr/src/debug/php8-8.1.29-lp156.3.2.x86_64/Zend/zend_vm_execute.h:1981
#8  0x00005b7fcae7760c in execute_ex (ex=0x5b7fcbe2dfa0) at /usr/src/debug/php8-8.1.29-lp156.3.2.x86_64/Zend/zend_vm_execute.h:55852
#9  0x00005b7fcac16419 in ZEND_DO_FCALL_SPEC_OBSERVER_HANDLER () at /usr/src/debug/php8-8.1.29-lp156.3.2.x86_64/Zend/zend_vm_execute.h:1946
#10 0x00005b7fcae7760c in execute_ex (ex=0x5b7fcbe2dfa0) at /usr/src/debug/php8-8.1.29-lp156.3.2.x86_64/Zend/zend_vm_execute.h:55852
#11 0x00005b7fcac16419 in ZEND_DO_FCALL_SPEC_OBSERVER_HANDLER () at /usr/src/debug/php8-8.1.29-lp156.3.2.x86_64/Zend/zend_vm_execute.h:1946
#12 0x00005b7fcae7760c in execute_ex (ex=0x5b7fcbe2dfa0) at /usr/src/debug/php8-8.1.29-lp156.3.2.x86_64/Zend/zend_vm_execute.h:55852
#13 0x00005b7fcac16419 in ZEND_DO_FCALL_SPEC_OBSERVER_HANDLER () at /usr/src/debug/php8-8.1.29-lp156.3.2.x86_64/Zend/zend_vm_execute.h:1946
...

@zherczeg
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mov %rdi,0x28(%rsp) if this instruction is crashing, we definitely have a stack problem, since rsp is the stack pointer. It looks like it cannot store a data there.

Try x/x $rsp+0x28, which should print something that the memory is not accessible.

Based on your backtrace, there is a lot of ZEND_DO_FCALL_SPEC_OBSERVER_HANDLER/execute_ex recursive calling.

@cmb69
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cmb69 commented Sep 14, 2024

Based on your backtrace, there is a lot of ZEND_DO_FCALL_SPEC_OBSERVER_HANDLER/execute_ex recursive calling.

execute_ex is the main executor; if it's called recursively, that is usually because some PHP code calls back into the engine. In this case that might be caused by Xdebug (a PHP code debugger).

For only PHP related issues, see php/php-src#15199 (comment).

@zherczeg
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It looks like you need to increase the stack space or reduce the recursive depth. The function allocates 0x2c8 bytes, which is surprising considering the function is simple. Perhaps the code is compiled in debug mode.

Anyway this does not feels like a pcre2 issue.

@carenas carenas mentioned this issue Oct 8, 2024
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@archon810 @zherczeg @cmb69