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Fix volatile-safety issue in pltcl_SPI_execute_plan().
The "callargs" variable is modified within PG_TRY and then referenced within PG_CATCH, which is exactly the coding pattern we've now found to be unsafe. Marking "callargs" volatile would be problematic because it is passed by reference to some Tcl functions, so fix the problem by not modifying it within PG_TRY. We can just postpone the free() till we exit the PG_TRY construct, as is already done elsewhere in this same file. Also, fix failure to free(callargs) when exiting on too-many-arguments error. This is only a minor memory leak, but a leak nonetheless. In passing, remove some unnecessary "volatile" markings in the same function. Those doubtless are there because gcc 2.95.3 whinged about them, but we now know that its algorithm for complaining is many bricks shy of a load. This is certainly a live bug with compilers that optimize similarly to current gcc, so back-patch to all active branches.
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src/pl/tcl/pltcl.c

Lines changed: 8 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -2156,9 +2156,9 @@ pltcl_SPI_execute_plan(ClientData cdata, Tcl_Interp *interp,
21562156
int j;
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Tcl_HashEntry *hashent;
21582158
pltcl_query_desc *qdesc;
2159-
const char *volatile nulls = NULL;
2160-
CONST84 char *volatile arrayname = NULL;
2161-
CONST84 char *volatile loop_body = NULL;
2159+
const char *nulls = NULL;
2160+
CONST84 char *arrayname = NULL;
2161+
CONST84 char *loop_body = NULL;
21622162
int count = 0;
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int callnargs;
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CONST84 char **callargs = NULL;
@@ -2288,6 +2288,8 @@ pltcl_SPI_execute_plan(ClientData cdata, Tcl_Interp *interp,
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if (i != argc)
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{
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Tcl_SetResult(interp, usage, TCL_STATIC);
2291+
if (callargs)
2292+
ckfree((char *) callargs);
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return TCL_ERROR;
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}
22932295

@@ -2326,10 +2328,6 @@ pltcl_SPI_execute_plan(ClientData cdata, Tcl_Interp *interp,
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}
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}
23282330

2329-
if (callargs)
2330-
ckfree((char *) callargs);
2331-
callargs = NULL;
2332-
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/************************************************************
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* Execute the plan
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************************************************************/
@@ -2356,6 +2354,9 @@ pltcl_SPI_execute_plan(ClientData cdata, Tcl_Interp *interp,
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}
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PG_END_TRY();
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2357+
if (callargs)
2358+
ckfree((char *) callargs);
2359+
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return my_rc;
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}
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