CVE-2015-1819 Enforce the reader to run in constant memory
One of the operation on the reader could resolve entities
leading to the classic expansion issue. Make sure the
buffer used for xmlreader operation is bounded.
Introduce a new allocation type for the buffers for this effect.
diff --git a/buf.c b/buf.c
index 6efc7b6..07922ff 100644
--- a/buf.c
+++ b/buf.c
@@ -27,6 +27,7 @@
#include <libxml/tree.h>
#include <libxml/globals.h>
#include <libxml/tree.h>
+#include <libxml/parserInternals.h> /* for XML_MAX_TEXT_LENGTH */
#include "buf.h"
#define WITH_BUFFER_COMPAT
@@ -299,7 +300,8 @@
if ((scheme == XML_BUFFER_ALLOC_DOUBLEIT) ||
(scheme == XML_BUFFER_ALLOC_EXACT) ||
(scheme == XML_BUFFER_ALLOC_HYBRID) ||
- (scheme == XML_BUFFER_ALLOC_IMMUTABLE)) {
+ (scheme == XML_BUFFER_ALLOC_IMMUTABLE) ||
+ (scheme == XML_BUFFER_ALLOC_BOUNDED)) {
buf->alloc = scheme;
if (buf->buffer)
buf->buffer->alloc = scheme;
@@ -458,6 +460,18 @@
size = buf->use + len + 100;
#endif
+ if (buf->alloc == XML_BUFFER_ALLOC_BOUNDED) {
+ /*
+ * Used to provide parsing limits
+ */
+ if ((buf->use + len >= XML_MAX_TEXT_LENGTH) ||
+ (buf->size >= XML_MAX_TEXT_LENGTH)) {
+ xmlBufMemoryError(buf, "buffer error: text too long\n");
+ return(0);
+ }
+ if (size >= XML_MAX_TEXT_LENGTH)
+ size = XML_MAX_TEXT_LENGTH;
+ }
if ((buf->alloc == XML_BUFFER_ALLOC_IO) && (buf->contentIO != NULL)) {
size_t start_buf = buf->content - buf->contentIO;
@@ -739,6 +753,15 @@
CHECK_COMPAT(buf)
if (buf->alloc == XML_BUFFER_ALLOC_IMMUTABLE) return(0);
+ if (buf->alloc == XML_BUFFER_ALLOC_BOUNDED) {
+ /*
+ * Used to provide parsing limits
+ */
+ if (size >= XML_MAX_TEXT_LENGTH) {
+ xmlBufMemoryError(buf, "buffer error: text too long\n");
+ return(0);
+ }
+ }
/* Don't resize if we don't have to */
if (size < buf->size)
@@ -867,6 +890,15 @@
needSize = buf->use + len + 2;
if (needSize > buf->size){
+ if (buf->alloc == XML_BUFFER_ALLOC_BOUNDED) {
+ /*
+ * Used to provide parsing limits
+ */
+ if (needSize >= XML_MAX_TEXT_LENGTH) {
+ xmlBufMemoryError(buf, "buffer error: text too long\n");
+ return(-1);
+ }
+ }
if (!xmlBufResize(buf, needSize)){
xmlBufMemoryError(buf, "growing buffer");
return XML_ERR_NO_MEMORY;
@@ -938,6 +970,15 @@
}
needSize = buf->use + len + 2;
if (needSize > buf->size){
+ if (buf->alloc == XML_BUFFER_ALLOC_BOUNDED) {
+ /*
+ * Used to provide parsing limits
+ */
+ if (needSize >= XML_MAX_TEXT_LENGTH) {
+ xmlBufMemoryError(buf, "buffer error: text too long\n");
+ return(-1);
+ }
+ }
if (!xmlBufResize(buf, needSize)){
xmlBufMemoryError(buf, "growing buffer");
return XML_ERR_NO_MEMORY;