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Fix ExecuteCallStmt to not scribble on the passed-in parse tree.
Sun, 4 Nov 2018 19:50:55 +0000 (14:50 -0500)
Sun, 4 Nov 2018 19:50:55 +0000 (14:50 -0500)
Modifying the parse tree at execution time is, or at least ought to be,
verboten. It seems quite difficult to actually cause a crash this way
in v11 (although you can exhibit it pretty easily in HEAD by messing
with plan_cache_mode). Nonetheless, it's risky, so fix and back-patch.

Discussion: https://postgr.es/m/13789.1541359611@sss.pgh.pa.us


diff --git a/src/backend/commands/functioncmds.c b/src/backend/commands/functioncmds.c
index 3fd73a69f04ff16afd00e07efde9c533c49e0aea..3925fb83a5438e09fb1f5dee5c9f77f71170ed54 100644 (file)
--- a/src/backend/commands/functioncmds.c
+++ b/src/backend/commands/functioncmds.c
@@ -2225,6 +2225,7 @@ ExecuteCallStmt(CallStmt *stmt, ParamListInfo params, bool atomic, DestReceiver
fexpr = stmt->funcexpr;
Assert(fexpr);
+ Assert(IsA(fexpr, FuncExpr));
aclresult = pg_proc_aclcheck(fexpr->funcid, GetUserId(), ACL_EXECUTE);
if (aclresult != ACLCHECK_OK)
@@ -2253,13 +2254,25 @@ ExecuteCallStmt(CallStmt *stmt, ParamListInfo params, bool atomic, DestReceiver
* and AbortTransaction() resets the security context. This could be
* reorganized, but right now it doesn't work.
*/
- if (((Form_pg_proc )GETSTRUCT(tp))->prosecdef)
+ if (((Form_pg_proc) GETSTRUCT(tp))->prosecdef)
callcontext->atomic = true;
/*
- * Expand named arguments, defaults, etc.
+ * Expand named arguments, defaults, etc. We do not want to scribble on
+ * the passed-in CallStmt parse tree, so first flat-copy fexpr, allowing
+ * us to replace its args field. (Note that expand_function_arguments
+ * will not modify any of the passed-in data structure.)
*/
- fexpr->args = expand_function_arguments(fexpr->args, fexpr->funcresulttype, tp);
+ {
+ FuncExpr *nexpr = makeNode(FuncExpr);
+
+ memcpy(nexpr, fexpr, sizeof(FuncExpr));
+ fexpr = nexpr;
+ }
+
+ fexpr->args = expand_function_arguments(fexpr->args,
+ fexpr->funcresulttype,
+ tp);
nargs = list_length(fexpr->args);
ReleaseSysCache(tp);
@@ -2362,8 +2375,8 @@ TupleDesc
CallStmtResultDesc(CallStmt *stmt)
{
FuncExpr *fexpr;
- HeapTuple tuple;
- TupleDesc tupdesc;
+ HeapTuple tuple;
+ TupleDesc tupdesc;
fexpr = stmt->funcexpr;
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