[OpenSIPS-Devel] [opensips] set local variable memory to 0 to prevent core dump (#507)

[Jarrod Baumann]

I didn't read the docs to find out cachedb_cassandra wasn't supported with db_cachedb so when I enabled it opensips was seg faulting.  This would probably need to be added to the declaration for other engines.

The cachedb_engine variable `cde` in `mod_init` (cachedb_cassandra.c:100) doesn't explicitly set the translation functions of the stack variable to NULL so the check in `db_cachedb_query` (db_cachedb/dbase.c:132) is passed and the db_query_trans tries to execute which faults:

## Before
```
Breakpoint 1, db_cachedb_query (_h=0x7ffff74221a8, _k=0x7fffffffe140, _op=0x0, 
    _v=0x7fffffffe1a0, _c=0x7fffffffe150, _n=1, _nc=1, _o=0x0, 
    _r=0x7fffffffe160) at dbase.c:129
warning: Source file is more recent than executable.
129	{
(gdb) n
130		struct db_cachedb_con* ptr = (struct db_cachedb_con *)_h->tail;
(gdb) n
132		if (ptr->cdbf.db_query_trans == NULL) {
(gdb) n
137		return ptr->cdbf.db_query_trans(ptr->cdbc,_h->table,_k,_op,_v,_c,_n,_nc,_o,_r);
(gdb) print *ptr->cdbf.db_query_trans
$1 = {int (cachedb_con *, const str *, const db_key_t *, const db_op_t *, 
    const db_val_t *, const db_key_t *, const int, const int, const db_key_t, 
    db_res_t **)} 0x7ffff7420aa8
(gdb) n

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff7420aa8 in ?? ()
```

## After
```
Breakpoint 1, db_cachedb_query (_h=0x7ffff74221a8, _k=0x7fffffffe140, _op=0x0, 
    _v=0x7fffffffe1a0, _c=0x7fffffffe150, _n=1, _nc=1, _o=0x0, 
    _r=0x7fffffffe160) at dbase.c:129
warning: Source file is more recent than executable.
129	{
(gdb) n
130		struct db_cachedb_con* ptr = (struct db_cachedb_con *)_h->tail;
(gdb) n
132		if (ptr->cdbf.db_query_trans == NULL) {
(gdb) n
133			LM_ERR("The selected NoSQL driver cannot convert select queries\n");
(gdb) n
134			return -1;
```

You can view, comment on, or merge this pull request online at:

  https://github.com/OpenSIPS/opensips/pull/507

-- Commit Summary --

  * set local variable memory to 0 to prevent core dump

-- File Changes --

    M modules/cachedb_cassandra/cachedb_cassandra.c (2)

-- Patch Links --

https://github.com/OpenSIPS/opensips/pull/507.patch
https://github.com/OpenSIPS/opensips/pull/507.diff

---
Reply to this email directly or view it on GitHub:
https://github.com/OpenSIPS/opensips/pull/507
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