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parser: Improve detection of entity loops

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Set a flag to detect entity loops at once instead of processing until
the depth limit is exceeded.
This commit is contained in:
Nick Wellnhofer 2022-12-23 21:29:28 +01:00
parent d972393f30
commit a41b09c739
5 changed files with 61 additions and 15 deletions
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5
include/private/entities.h
View File

@ -13,8 +13,9 @@
*/
#define XML_ENT_PARSED (1<<0)
#define XML_ENT_CHECKED (1<<1)
#define XML_ENT_CHECKED_LT (1<<2)
#define XML_ENT_CONTAINS_LT (1<<3)
#define XML_ENT_EXPANDING (1<<2)
#define XML_ENT_CHECKED_LT (1<<3)
#define XML_ENT_CONTAINS_LT (1<<4)
XML_HIDDEN xmlChar *
xmlEncodeAttributeEntities(xmlDocPtr doc, const xmlChar *input);

53
parser.c
View File

@ -2228,6 +2228,8 @@ xmlSkipBlankChars(xmlParserCtxtPtr ctxt) {
*/
xmlChar
xmlPopInput(xmlParserCtxtPtr ctxt) {
xmlParserInputPtr input;
if ((ctxt == NULL) || (ctxt->inputNr <= 1)) return(0);
if (xmlParserDebugEntities)
xmlGenericError(xmlGenericErrorContext,
@ -2236,7 +2238,10 @@ xmlPopInput(xmlParserCtxtPtr ctxt) {
(ctxt->instate != XML_PARSER_EOF))
xmlFatalErr(ctxt, XML_ERR_INTERNAL_ERROR,
"Unfinished entity outside the DTD");
xmlFreeInputStream(inputPop(ctxt));
input = inputPop(ctxt);
if (input->entity != NULL)
input->entity->flags &= ~XML_ENT_EXPANDING;
xmlFreeInputStream(input);
if (*ctxt->input->cur == 0)
xmlParserInputGrow(ctxt->input, INPUT_CHUNK);
return(CUR);
@ -2621,7 +2626,8 @@ xmlStringDecodeEntitiesInt(xmlParserCtxtPtr ctxt, const xmlChar *str, int len,
if (((ctxt->depth > 40) &&
((ctxt->options & XML_PARSE_HUGE) == 0)) ||
(ctxt->depth > 1024)) {
xmlFatalErr(ctxt, XML_ERR_ENTITY_LOOP, NULL);
xmlFatalErrMsg(ctxt, XML_ERR_ENTITY_LOOP,
"Maximum entity nesting depth exceeded");
return(NULL);
}
@ -2675,10 +2681,20 @@ xmlStringDecodeEntitiesInt(xmlParserCtxtPtr ctxt, const xmlChar *str, int len,
if ((check) && (xmlParserEntityCheck(ctxt, ent->length)))
goto int_error;
if (ent->flags & XML_ENT_EXPANDING) {
xmlFatalErr(ctxt, XML_ERR_ENTITY_LOOP, NULL);
xmlHaltParser(ctxt);
ent->content[0] = 0;
goto int_error;
}
ent->flags |= XML_ENT_EXPANDING;
ctxt->depth++;
rep = xmlStringDecodeEntitiesInt(ctxt, ent->content,
ent->length, what, 0, 0, 0, check);
ctxt->depth--;
ent->flags &= ~XML_ENT_EXPANDING;
if (rep == NULL) {
ent->content[0] = 0;
goto int_error;
@ -2732,10 +2748,20 @@ xmlStringDecodeEntitiesInt(xmlParserCtxtPtr ctxt, const xmlChar *str, int len,
if ((check) && (xmlParserEntityCheck(ctxt, ent->length)))
goto int_error;
if (ent->flags & XML_ENT_EXPANDING) {
xmlFatalErr(ctxt, XML_ERR_ENTITY_LOOP, NULL);
xmlHaltParser(ctxt);
ent->content[0] = 0;
goto int_error;
}
ent->flags |= XML_ENT_EXPANDING;
ctxt->depth++;
rep = xmlStringDecodeEntitiesInt(ctxt, ent->content,
ent->length, what, 0, 0, 0, check);
ctxt->depth--;
ent->flags &= ~XML_ENT_EXPANDING;
if (rep == NULL) {
if (ent->content != NULL)
ent->content[0] = 0;
@ -7237,6 +7263,14 @@ xmlParseReference(xmlParserCtxtPtr ctxt) {
/* Avoid overflow as much as possible */
ctxt->sizeentcopy = 0;
if (ent->flags & XML_ENT_EXPANDING) {
xmlFatalErr(ctxt, XML_ERR_ENTITY_LOOP, NULL);
xmlHaltParser(ctxt);
return;
}
ent->flags |= XML_ENT_EXPANDING;
/*
* Check that this entity is well formed
* 4.3.2: An internal general parsed entity is well-formed
@ -7261,6 +7295,7 @@ xmlParseReference(xmlParserCtxtPtr ctxt) {
"invalid entity type found\n", NULL);
}
ent->flags &= ~XML_ENT_EXPANDING;
ent->flags |= XML_ENT_PARSED | XML_ENT_CHECKED;
ent->expandedSize = ctxt->sizeentcopy;
if (ret == XML_ERR_ENTITY_LOOP) {
@ -8033,6 +8068,12 @@ xmlParsePEReference(xmlParserCtxtPtr ctxt)
(ctxt->validate == 0))
return;
if (entity->flags & XML_ENT_EXPANDING) {
xmlFatalErr(ctxt, XML_ERR_ENTITY_LOOP, NULL);
xmlHaltParser(ctxt);
return;
}
parentConsumed = ctxt->input->parentConsumed;
xmlSaturatedAdd(&parentConsumed, ctxt->input->consumed);
xmlSaturatedAddSizeT(&parentConsumed,
@ -8044,6 +8085,8 @@ xmlParsePEReference(xmlParserCtxtPtr ctxt)
return;
}
entity->flags |= XML_ENT_EXPANDING;
input->parentConsumed = parentConsumed;
if (entity->etype == XML_EXTERNAL_PARAMETER_ENTITY) {
@ -12776,7 +12819,8 @@ xmlParseExternalEntityPrivate(xmlDocPtr doc, xmlParserCtxtPtr oldctxt,
if (((depth > 40) &&
((oldctxt == NULL) || (oldctxt->options & XML_PARSE_HUGE) == 0)) ||
(depth > 1024)) {
xmlFatalErr(oldctxt, XML_ERR_ENTITY_LOOP, NULL);
xmlFatalErrMsg(oldctxt, XML_ERR_ENTITY_LOOP,
"Maximum entity nesting depth exceeded");
return(XML_ERR_ENTITY_LOOP);
}
@ -13065,7 +13109,8 @@ xmlParseBalancedChunkMemoryInternal(xmlParserCtxtPtr oldctxt,
if (((oldctxt->depth > 40) && ((oldctxt->options & XML_PARSE_HUGE) == 0)) ||
(oldctxt->depth > 1024)) {
xmlFatalErr(oldctxt, XML_ERR_ENTITY_LOOP, NULL);
xmlFatalErrMsg(oldctxt, XML_ERR_ENTITY_LOOP,
"Maximum entity nesting depth exceeded");
return(XML_ERR_ENTITY_LOOP);
}

6
result/errors/759579.xml.ent
View File

@ -1,6 +1,6 @@
Entity: line 2: parser error : Detected an entity reference loop
%z; %z; %z; %z; %z;
^
./test/errors/759579.xml:9: parser error : Detected an entity reference loop
%z;
^
Entity: line 2:
%z; %z; %z; %z; %z;
^

6
result/errors/759579.xml.err
View File

@ -1,6 +1,6 @@
Entity: line 2: parser error : Detected an entity reference loop
%z; %z; %z; %z; %z;
^
./test/errors/759579.xml:9: parser error : Detected an entity reference loop
%z;
^
Entity: line 2:
%z; %z; %z; %z; %z;
^

6
result/errors/759579.xml.str
View File

@ -1,6 +1,6 @@
Entity: line 2: parser error : Detected an entity reference loop
%z; %z; %z; %z; %z;
^
./test/errors/759579.xml:9: parser error : Detected an entity reference loop
%z;
^
Entity: line 2:
%z; %z; %z; %z; %z;
^