repeatable pgsql segfault in session reset timeout #5039
Description
When using a postgres backend, proxysql segfaults if there's a timeout running the DISCARD ALL command to make the backend connection ready for reuse.
This repo inserts a transparent tcp proxy between proxysql and the postgresql backend, to add a delay to the DISCARD ALL command and trigger the segfault.
- have a local postgres server with a user
testand passwordtesttest - start the proxy (attached) in the background:
./psql-proxy-delay-discard.py &
- launch proxysql, with
PGSSLMODE=disablein the environment to ensure no ssl to the backend, so that the proxy can see and react to theDISCARD ALL:
PGSSLMODE=disable /home/admin/proxysql -c /home/admin/proxysql.cnf -f --idle-threads -D /tmp/proxysql &
- Connect through proxysql, issue a SET command so that a reset will be needed, disconnect:
psql -h 127.0.0.1 -U test -p 6133 -d postgres -c 'set search_path to public'
Password for user test:
2025-07-10 10:01:36 PgSQL_Session.cpp:5774:unable_to_parse_set_statement(): [WARNING] Unable to parse unknown SET query from client 127.0.0.1:38080. Setting lock_hostgroup. Please report a bug for future enhancements:set search_path to public
> '\x00\x00\x00Å\x00\x03\x00\x00user\x00test\x00database\x00postgres\x00options\x00-c datestyle=ISO,\\ MDY -c intervalstyle=postgres -c standard_conforming_strings=on -c timezone=GMT \x00application_name\x00proxysql\x00client_encoding\x00SQL_ASCII\x00\x00'
< 'R\x00\x00\x00\x17\x00\x00\x00\nSCRAM-SHA-256\x00\x00'
> 'p\x00\x00\x006SCRAM-SHA-256\x00\x00\x00\x00 n,,n=,r=TwnJBOUKdlXFZGk/ZOAc7/R5'
< 'R\x00\x00\x00\\\x00\x00\x00\x0br=TwnJBOUKdlXFZGk/ZOAc7/R5BokVXq0xssJ/2ntpyWfFnCZu,s=lR+4HjuMXUe8rsCLeurCRQ==,i=4096'
> 'p\x00\x00\x00lc=biws,r=TwnJBOUKdlXFZGk/ZOAc7/R5BokVXq0xssJ/2ntpyWfFnCZu,p=ESBQijzVAC7XrNsM7ShghrOVzRmhkaXxmtc/YONCUp8='
< 'R\x00\x00\x006\x00\x00\x00\x0cv=hPBeEcHrACHvKUxFctYm1Zv5vJxNaJDpquXtG6fjKa0=R\x00\x00\x00\x08\x00\x00\x00\x00S\x00\x00\x00\x17in_hot_standby\x00off\x00S\x00\x00\x00\x19integer_datetimes\x00on\x00S\x00\x00\x00\x11TimeZone\x00GMT\x00S\x00\x00\x00\x1bIntervalStyle\x00postgres\x00S\x00\x00\x00\x15is_superuser\x00off\x00S\x00\x00\x00\x1eapplication_name\x00proxysql\x00S\x00\x00\x00&default_transaction_read_only\x00off\x00S\x00\x00\x00\x1ascram_iterations\x004096\x00S\x00\x00\x00\x17DateStyle\x00ISO, MDY\x00S\x00\x00\x00#standard_conforming_strings\x00on\x00S\x00\x00\x00\x1fsession_authorization\x00test\x00S\x00\x00\x00\x1eclient_encoding\x00SQL_ASCII\x00S\x00\x00\x002server_version\x0017.5 (Debian 17.5-1.pgdg120+1)\x00S\x00\x00\x00\x19server_encoding\x00UTF8\x00K\x00\x00\x00\x0c\x00\x00\x10 x\x14É\x13Z\x00\x00\x00\x05I'
> 'Q\x00\x00\x00\x1eset search_path to public\x00'
< 'C\x00\x00\x00\x08SET\x00Z\x00\x00\x00\x05I'
SET
> 'Q\x00\x00\x00\x10DISCARD ALL\x00'
delaying DISCARD command
admin@ip-172-31-35-238:~$ 2025-07-10 10:01:37 PgSQL_Session.cpp:1315:handler_again___status_RESETTING_CONNECTION(): [ERROR] Resetting Connection timeout during Reset Session on 127.0.0.1 , 7001
Error: signal 11:
/home/admin/proxysql(_Z13crash_handleri+0x2a)[0x55be45b9ef0a]
/lib/x86_64-linux-gnu/libc.so.6(+0x3c050)[0x7f14e645b050]
/lib/x86_64-linux-gnu/libc.so.6(+0x1679d8)[0x7f14e65869d8]
/home/admin/proxysql(_ZN13PgSQL_Session10RequestEndEP17PgSQL_Data_StreamjPKc+0x193)[0x55be45dcf2e3]
/home/admin/proxysql(_ZN13PgSQL_Session43handler_again___status_RESETTING_CONNECTIONEv+0x198)[0x55be45dcd688]
/home/admin/proxysql(_ZN13PgSQL_Session7handlerEv+0x268)[0x55be45dddc88]
/home/admin/proxysql(_ZN12PgSQL_Thread20process_all_sessionsEv+0x3b6)[0x55be45dc67c6]
/home/admin/proxysql(_ZN12PgSQL_Thread3runEv+0x54c)[0x55be45dc6fac]
/home/admin/proxysql(_Z24pgsql_worker_thread_funcPv+0xec)[0x55be45b6fc23]
/lib/x86_64-linux-gnu/libc.so.6(+0x891f5)[0x7f14e64a81f5]
/lib/x86_64-linux-gnu/libc.so.6(+0x10989c)[0x7f14e652889c]
---- /home/admin/proxysql(_Z13crash_handleri+0x2a) [0x55be45b9ef0a] : crash_handler(int)
---- /home/admin/proxysql(_ZN13PgSQL_Session10RequestEndEP17PgSQL_Data_StreamjPKc+0x193) [0x55be45dcf2e3] : PgSQL_Session::RequestEnd(PgSQL_Data_Stream*, unsigned int, char const*)
---- /home/admin/proxysql(_ZN13PgSQL_Session43handler_again___status_RESETTING_CONNECTIONEv+0x198) [0x55be45dcd688] : PgSQL_Session::handler_again___status_RESETTING_CONNECTION()
---- /home/admin/proxysql(_ZN13PgSQL_Session7handlerEv+0x268) [0x55be45dddc88] : PgSQL_Session::handler()
---- /home/admin/proxysql(_ZN12PgSQL_Thread20process_all_sessionsEv+0x3b6) [0x55be45dc67c6] : PgSQL_Thread::process_all_sessions()
---- /home/admin/proxysql(_ZN12PgSQL_Thread3runEv+0x54c) [0x55be45dc6fac] : PgSQL_Thread::run()
---- /home/admin/proxysql(_Z24pgsql_worker_thread_funcPv+0xec) [0x55be45b6fc23] : pgsql_worker_thread_func(void*)
To report a crashing bug visit: https://github.com/sysown/proxysql/issues
For support visit: https://proxysql.com/services/support/
> 'X\x00\x00\x00\x04'
< 'C\x00\x00\x00\x10DISCARD ALL\x00Z\x00\x00\x00\x05I'
[2]+ Segmentation fault (core dumped) PGSSLMODE=disable /home/admin/proxysql -c /home/admin/proxysql.cnf -f --idle-threads -D /tmp/proxysql
The proxysql binary was copied from the proxysql/proxysql 3.0.1-debian image on docker.io.
/home/admin/proxysql --version
2025-07-10 10:38:24 [INFO] Using OpenSSL version: OpenSSL 3.0.15 3 Sep 2024
2025-07-10 10:38:24 main.cpp:348:check_openssl_version(): [WARNING] Detected OpenSSL version has known performance regressions, please upgrade to '3.2.0' or later. For further details, please refer to: https://github.com/openssl/openssl/issues/18814
ProxySQL version 3.0.1-420-g2c26a42, codename Truls