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Commite060cd5

Browse files
committed
Avoid copying undefined data in _readA_Const().
nodeRead() will have created a Node struct that's only allocated bigenough for the specific node type, so copying sizeof(union ValUnion)can be copying too much. This provokes valgrind complaints, and withvery bad luck could perhaps result in SIGSEGV.While at it, tidy up _equalA_Const to avoid duplicate checks of isnull.Per report from Alexander Lakhin. This code is new as ofa6bc330,so no need to back-patch.Discussion:https://postgr.es/m/4995256b-cc65-170e-0b22-60ad2cd535f1@gmail.com
1 parent4f46f87 commite060cd5

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2 files changed

+27
-6
lines changed

2 files changed

+27
-6
lines changed

‎src/backend/nodes/equalfuncs.c

Lines changed: 3 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -133,13 +133,11 @@ _equalExtensibleNode(const ExtensibleNode *a, const ExtensibleNode *b)
133133
staticbool
134134
_equalA_Const(constA_Const*a,constA_Const*b)
135135
{
136-
/*
137-
* Hack for in-line val field. Also val is not valid is isnull is true.
138-
*/
139-
if (!a->isnull&& !b->isnull&&
136+
COMPARE_SCALAR_FIELD(isnull);
137+
/* Hack for in-line val field. Also val is not valid if isnull is true */
138+
if (!a->isnull&&
140139
!equal(&a->val,&b->val))
141140
return false;
142-
COMPARE_SCALAR_FIELD(isnull);
143141
COMPARE_LOCATION_FIELD(location);
144142

145143
return true;

‎src/backend/nodes/readfuncs.c

Lines changed: 24 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -305,14 +305,37 @@ _readA_Const(void)
305305
{
306306
READ_LOCALS(A_Const);
307307

308+
/* We expect either NULL or :val here */
308309
token=pg_strtok(&length);
309310
if (length==4&&strncmp(token,"NULL",4)==0)
310311
local_node->isnull= true;
311312
else
312313
{
313314
unionValUnion*tmp=nodeRead(NULL,0);
314315

315-
memcpy(&local_node->val,tmp,sizeof(*tmp));
316+
/* To forestall valgrind complaints, copy only the valid data */
317+
switch (nodeTag(tmp))
318+
{
319+
caseT_Integer:
320+
memcpy(&local_node->val,tmp,sizeof(Integer));
321+
break;
322+
caseT_Float:
323+
memcpy(&local_node->val,tmp,sizeof(Float));
324+
break;
325+
caseT_Boolean:
326+
memcpy(&local_node->val,tmp,sizeof(Boolean));
327+
break;
328+
caseT_String:
329+
memcpy(&local_node->val,tmp,sizeof(String));
330+
break;
331+
caseT_BitString:
332+
memcpy(&local_node->val,tmp,sizeof(BitString));
333+
break;
334+
default:
335+
elog(ERROR,"unrecognized node type: %d",
336+
(int)nodeTag(tmp));
337+
break;
338+
}
316339
}
317340

318341
READ_LOCATION_FIELD(location);

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