Re: [BUG] CRASH: ECPGprepared_statement() and ECPGdeallocate_all() when connection is NULL

Hello hackers,

01.05.2026 22:20, Andrew Dunstan wrote:
>
> On Wed, Apr 22, 2026 at 12:27 AM Nishant Sharma <nishant.sharma@enterprisedb.com> wrote:
>
>     Thanks Shruthi!
>
>     v5 code, v4_test and v4_test_15 patches look good to me.
>
>     I checked ECPG regression on master, REL_18, REL_17, REL_16, REL_15, REL_14 using both make and meson.
>
>     I have finished my review work on the patches. Thank you!
>
>
> Thanks, everybody, pushed (as combined patches)

Despite this improvement committed, dikkop keeps producing segfaults
during ecpg test, e.g., [1], [2]:
ok 62        - thread/thread_implicit                    224 ms
not ok 63    - thread/prep                               116 ms
# (test process was terminated by signal 11: Segmentation fault)
ok 64        - thread/alloc                              406 ms

There is no other useful information in the log, so it's not clear what's
wrong with that animal (no other gives us such failures), but I could
produce something similar (on FreeBSD and Linux) with:
echo "max_connections = 10" >/tmp/temp.config; TEMP_CONFIG=/tmp/temp.config gmake -s check -C src/interfaces/ecpg/test

not ok 64    - thread/prep                                29 ms
# (test process was terminated by signal 11: Segmentation fault)

not ok 65    - thread/alloc                               27 ms
# (test process was terminated by signal 11: Segmentation fault)

gdb src/interfaces/ecpg/test/thread/prep src/interfaces/ecpg/test/core.3371028
Core was generated by `.../src/interfaces/ecpg/test/thread/prep'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x00007478ad3a8301 in deallocate_one (lineno=lineno@entry=45, c=c@entry=ECPG_COMPAT_PGSQL, 
con=con@entry=0x747888000ca0, prev=0x0, this=0x74788800ad40)
     at prepare.c:313
313 this->stmt->connection->connection,
[Current thread is 1 (Thread 0x7478a1c006c0 (LWP 3371041))]
(gdb) bt
#0  0x00007478ad3a8301 in deallocate_one (lineno=lineno@entry=45, c=c@entry=ECPG_COMPAT_PGSQL, 
con=con@entry=0x747888000ca0, prev=0x0, this=0x74788800ad40)
     at prepare.c:313
#1  0x00007478ad3a8a32 in ECPGprepare (lineno=lineno@entry=45, connection_name=connection_name@entry=0x0, 
questionmarks=questionmarks@entry=false,
     name=name@entry=0x5d934a41b024 "i", variable=variable@entry=0x7478a1bffdb0 "INSERT INTO T VALUES ( ? )") at 
prepare.c:264
#2  0x00005d934a41a536 in fn (arg=<optimized out>) at .../src/interfaces/ecpg/test/thread/prep.pgc:45
#3  0x00007478ad09caa4 in start_thread (arg=<optimized out>) at ./nptl/pthread_create.c:447
#4  0x00007478ad129c3c in clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:78

(gdb) p this->stmt
$1 = (struct statement *) 0x242028205345554c
(gdb) p this->stmt->connection
Cannot access memory at address 0x2420282053455564

gdb src/interfaces/ecpg/test/thread/alloc src/interfaces/ecpg/test/core.3371068
Core was generated by `.../src/interfaces/ecpg/test/thread/alloc'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  pqRowProcessor (conn=conn@entry=0x7962f4000d60, errmsgp=errmsgp@entry=0x7963151ffbd0) at fe-exec.c:1226
1226            int                     nfields = res->numAttributes;
[Current thread is 1 (Thread 0x7963152006c0 (LWP 3371075))]
(gdb) bt
#0  pqRowProcessor (conn=conn@entry=0x7962f4000d60, errmsgp=errmsgp@entry=0x7963151ffbd0) at fe-exec.c:1226
#1  0x00007963188e9d44 in getAnotherTuple (conn=conn@entry=0x7962f4000d60, msgLength=14) at fe-protocol3.c:849
#2  0x00007963188eb42b in pqParseInput3 (conn=conn@entry=0x7962f4000d60) at fe-protocol3.c:388
#3  0x00007963188e0e69 in parseInput (conn=conn@entry=0x7962f4000d60) at fe-exec.c:2039
#4  0x00007963188e3d74 in PQgetResult (conn=conn@entry=0x7962f4000d60) at fe-exec.c:2125
#5  0x00007963188e3fec in PQexecStart (conn=conn@entry=0x7962f4000d60) at fe-exec.c:2386
#6  0x00007963188e40a7 in PQexec (conn=0x7962f4000d60, query=0x7962e8000ca0 "select relname from pg_class where relname 
= 'pg_class'") at fe-exec.c:2281
#7  0x0000796318948620 in ecpg_execute (stmt=0x7962e8009e60) at execute.c:1619
#8  0x00007963189494fc in ecpg_do (lineno=<optimized out>, compat=<optimized out>, force_indicator=<optimized out>, 
connection_name=<optimized out>,
     questionmarks=questionmarks@entry=false, st=<optimized out>, query=0x5a5947b97028 "select relname from pg_class 
where relname = 'pg_class'",
     args=0x7963151ffcf0) at execute.c:2273
#9  0x00007963189495b7 in ECPGdo (lineno=lineno@entry=45, compat=compat@entry=0, force_indicator=force_indicator@entry=1,
     connection_name=connection_name@entry=0x0, questionmarks=questionmarks@entry=false, st=st@entry=0,
     query=0x5a5947b97028 "select relname from pg_class where relname = 'pg_class'") at execute.c:2298
#10 0x00005a5947b963b8 in fn (arg=<optimized out>) at .../src/interfaces/ecpg/test/thread/alloc.pgc:45
#11 0x000079631869caa4 in start_thread (arg=<optimized out>) at ./nptl/pthread_create.c:447
#12 0x0000796318729c3c in clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:78
(gdb) p conn
$1 = (PGconn *) 0x7962f4000d60
(gdb) p conn->result
$2 = (PGresult *) 0x0

Could you please look if such crashes can be prevented too?

[1] https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=dikkop&dt=2026-05-04%2010%3A00%3A10
[2] https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=dikkop&dt=2026-05-03%2021%3A25%3A17

Best regards,
Alexander