session_start(): Failed to read session data: memcache using php7.2

[kmille]

Hey,

I tried some debugging but I think php is the problem:

php-fpm configuration

php_admin_value[session.save_handler] = memcache
php_admin_value[session.save_path] = tcp://10.100.128.54:11211, tcp://10.100.128.55:11211

Error message:

[12-Jul-2019 10:31:32 Europe/Berlin] PHP Warning:  session_start(): Failed to read session data: memcache (path: tcp://10.100.128.54:11211, tcp://10.100.128.55:11211) in /var/www/vhosts/cuschtomer/htdocs/backend/__test_dc1_memcached.php on line 11

Test file:

<?php

ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL);

#echo $_SERVER['SERVER_ADDR'];
#ini_set("memcache
session_start();
#$_SESSION["dc1"] = "test";
#echo $_SESSION["dc1"];
#phpinfo();
echo "done\n";
?>

ngrep log:

root@cuschtomer:~# ngrep -d any -q -W byline port 11211 and host 10.100.128.54
interface: any
filter: ( port 11211 and host 10.100.128.54 ) and (ip || ip6)

T 10.100.128.160:44808 -> 10.100.128.54:11211 [AP] #4
incr r9v63n79qkva4igrme08vce2n3.lock 1.

T 10.100.128.160:44808 -> 10.100.128.54:11211 [AP] #6
add r9v63n79qkva4igrme08vce2n3.lock 768 15 1.
1.
get r9v63n79qkva4igrme08vce2n3.

T 10.100.128.54:11211 -> 10.100.128.160:44808 [AP] #7
NOT_FOUND.

T 10.100.128.54:11211 -> 10.100.128.160:44808 [AP] #9
STORED.

T 10.100.128.54:11211 -> 10.100.128.160:44808 [AP] #11
END.

We are using php7.2-fpm on Ubuntu 18.04 with php-memcache (3.0.9~20160311.4991c2f-5build2). The Memcached server runs on Ubuntu 16.04 (1.4.25-2ubuntu1.2). There are no erros in the log file. Any idea what's wrong?

Greetings

kmille

[kmille]

any updates?

[tomassrnka]

Hi, sorry we are on holidays, i will take a look at it next week when im back.

[kmille]

Hey, still on holiday? We came across the same bug today after upgrading to 18.04 for a different customer.

[kmille]

For me it just looks like you return the wrong value. Like: return error; (even if everything works)
probably just this: https://github.com/php/php-src/blob/master/ext/session/session.c#L441
I currently don't have the time to make a PR (+ I don't exactly where I need to patch it)

[tomassrnka]

@kmille I tried to reproduce the bug, yes it is there with php-memcache from Ubuntu 18.04, however if you use latest release from this repo, it works as expected.
# php a.php
done

[tomassrnka]

@kmille -> could you please try it with current pecl-memcache extension from our repo? It should be pretty easy to build.

# install deps
apt-get install  php7.2-dev git make 

# Build extension
CFLAGS="-fstack-protector-strong -fpic -fpie -O2"
CPPFLAGS="$PHP_CFLAGS"
LDFLAGS="-Wl,-O1 -Wl,--hash-style=both -pie"
set -eux
cd /usr/src
git clone https://github.com/websupport-sk/pecl-memcache.git
cd pecl-memcache; 
phpize 
./configure 
make -j$(nproc)

# remove old one
apt-get remove php7.2-memcache # or php-memcache

make install 

[kmille]

Hey,
thanks for caring! We upgraded the system so I can't reproduce it anymore.