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Avoid possible longjmp-induced logic error in PLy_trigger_build_args.

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The "pltargs" variable wasn't marked volatile, which makes it unsafe
to change its value within the PG_TRY block.  It looks like the worst
outcome would be to fail to release a refcount on Py_None during an
(improbable) error exit, which would likely go unnoticed in the field.
Still, it's a bug.  A one-liner fix could be to mark pltargs volatile,
but on the whole it seems cleaner to arrange things so that we don't
change its value within PG_TRY.

Per report from Xing Guo.  This has been there for quite awhile,
so back-patch to all supported branches.

Discussion: https://postgr.es/m/CACpMh+DLrk=fDv07MNpBT4J413fDAm+gmMXgi8cjPONE+jvzuw@mail.gmail.com
This commit is contained in:
Tom Lane 2024-04-01 15:15:03 -04:00
parent de3c5b1872
commit fb60118bf2
1 changed files with 8 additions and 4 deletions
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12
src/pl/plpython/plpy_exec.c
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@ -693,7 +693,7 @@ PLy_trigger_build_args(FunctionCallInfo fcinfo, PLyProcedure *proc, HeapTuple *r
*pltrelid, *pltrelid,
*plttablename, *plttablename,
*plttableschema, *plttableschema,
*pltargs = NULL, *pltargs,
*pytnew, *pytnew,
*pytold, *pytold,
*pltdata; *pltdata;
@ -717,6 +717,11 @@ PLy_trigger_build_args(FunctionCallInfo fcinfo, PLyProcedure *proc, HeapTuple *r
return NULL; return NULL;
} }
} }
else
{
Py_INCREF(Py_None);
pltargs = Py_None;
}
PG_TRY(); PG_TRY();
{ {
@ -860,7 +865,7 @@ PLy_trigger_build_args(FunctionCallInfo fcinfo, PLyProcedure *proc, HeapTuple *r
PyObject *pltarg; PyObject *pltarg;
/* pltargs should have been allocated before the PG_TRY block. */ /* pltargs should have been allocated before the PG_TRY block. */
Assert(pltargs); Assert(pltargs && pltargs != Py_None);
for (i = 0; i < tdata->tg_trigger->tgnargs; i++) for (i = 0; i < tdata->tg_trigger->tgnargs; i++)
{ {
@ -874,8 +879,7 @@ PLy_trigger_build_args(FunctionCallInfo fcinfo, PLyProcedure *proc, HeapTuple *r
} }
else else
{ {
Py_INCREF(Py_None); Assert(pltargs == Py_None);
pltargs = Py_None;
} }
PyDict_SetItemString(pltdata, "args", pltargs); PyDict_SetItemString(pltdata, "args", pltargs);
Py_DECREF(pltargs); Py_DECREF(pltargs);