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Propagate memory errors in xmlXPathCompExprAdd

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Make sure that memory errors in xmlXPathCompExprAdd are propagated to
the parser context. Hitting the step limit or running out of memory
without raising an error could also lead to an out-of-bounds read.

Also fixes a memory leak in xmlXPathErrMemory.

Found by OSS-Fuzz.
This commit is contained in:
Nick Wellnhofer
2019-10-20 13:42:19 +02:00
parent aec2bf7153
commit 390f05e703
1 changed files with 10 additions and 8 deletions
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18
xpath.c
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@@ -627,6 +627,7 @@ static void
xmlXPathErrMemory(xmlXPathContextPtr ctxt, const char *extra)
{
if (ctxt != NULL) {
xmlResetError(&ctxt->lastError);
if (extra) {
xmlChar buf[200];
@@ -1104,14 +1105,15 @@ xmlXPathFreeCompExpr(xmlXPathCompExprPtr comp)
* Returns -1 in case of failure, the index otherwise
*/
static int
xmlXPathCompExprAdd(xmlXPathCompExprPtr comp, int ch1, int ch2,
xmlXPathCompExprAdd(xmlXPathParserContextPtr ctxt, int ch1, int ch2,
xmlXPathOp op, int value,
int value2, int value3, void *value4, void *value5) {
xmlXPathCompExprPtr comp = ctxt->comp;
if (comp->nbStep >= comp->maxStep) {
xmlXPathStepOp *real;
if (comp->maxStep >= XPATH_MAX_STEPS) {
xmlXPathErrMemory(NULL, "adding step\n");
xmlXPathPErrMemory(ctxt, "adding step\n");
return(-1);
}
comp->maxStep *= 2;
@@ -1119,7 +1121,7 @@ xmlXPathCompExprAdd(xmlXPathCompExprPtr comp, int ch1, int ch2,
comp->maxStep * sizeof(xmlXPathStepOp));
if (real == NULL) {
comp->maxStep /= 2;
xmlXPathErrMemory(NULL, "adding step\n");
xmlXPathPErrMemory(ctxt, "adding step\n");
return(-1);
}
comp->steps = real;
@@ -1181,20 +1183,20 @@ xmlXPathCompSwap(xmlXPathStepOpPtr op) {
}
#define PUSH_FULL_EXPR(op, op1, op2, val, val2, val3, val4, val5) \
xmlXPathCompExprAdd(ctxt->comp, (op1), (op2), \
xmlXPathCompExprAdd(ctxt, (op1), (op2), \
(op), (val), (val2), (val3), (val4), (val5))
#define PUSH_LONG_EXPR(op, val, val2, val3, val4, val5) \
xmlXPathCompExprAdd(ctxt->comp, ctxt->comp->last, -1, \
xmlXPathCompExprAdd(ctxt, ctxt->comp->last, -1, \
(op), (val), (val2), (val3), (val4), (val5))
#define PUSH_LEAVE_EXPR(op, val, val2) \
xmlXPathCompExprAdd(ctxt->comp, -1, -1, (op), (val), (val2), 0 ,NULL ,NULL)
xmlXPathCompExprAdd(ctxt, -1, -1, (op), (val), (val2), 0 ,NULL ,NULL)
#define PUSH_UNARY_EXPR(op, ch, val, val2) \
xmlXPathCompExprAdd(ctxt->comp, (ch), -1, (op), (val), (val2), 0 ,NULL ,NULL)
xmlXPathCompExprAdd(ctxt, (ch), -1, (op), (val), (val2), 0 ,NULL ,NULL)
#define PUSH_BINARY_EXPR(op, ch1, ch2, val, val2) \
xmlXPathCompExprAdd(ctxt->comp, (ch1), (ch2), (op), \
xmlXPathCompExprAdd(ctxt, (ch1), (ch2), (op), \
(val), (val2), 0 ,NULL ,NULL)
/************************************************************************