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author | Daniel Veillard <veillard@redhat.com> | 2015-04-14 17:41:48 +0800 |
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committer | Daniel Veillard <veillard@redhat.com> | 2015-04-14 17:41:48 +0800 |
commit | 213f1fe0d76d30eaed6e5853057defc43e6df2c9 (patch) | |
tree | 31a733dc047ef2ed98aab69d2ac38acac9442421 | |
parent | 8985cde70901c62d3f0f04da225e73b7344a52d7 (diff) | |
download | libxml2-213f1fe0d76d30eaed6e5853057defc43e6df2c9.tar.gz |
CVE-2015-1819 Enforce the reader to run in constant memoryCVE-2015-1819
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.
-rw-r--r-- | buf.c | 43 | ||||
-rw-r--r-- | include/libxml/tree.h | 3 | ||||
-rw-r--r-- | xmlreader.c | 20 |
3 files changed, 63 insertions, 3 deletions
@@ -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 @@ xmlBufSetAllocationScheme(xmlBufPtr buf, 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 @@ xmlBufGrowInternal(xmlBufPtr buf, size_t len) { 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 @@ xmlBufResize(xmlBufPtr buf, size_t size) 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 @@ xmlBufAdd(xmlBufPtr buf, const xmlChar *str, int len) { 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 @@ xmlBufAddHead(xmlBufPtr buf, const xmlChar *str, int len) { } 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; diff --git a/include/libxml/tree.h b/include/libxml/tree.h index 2f90717c..4a9b3bc6 100644 --- a/include/libxml/tree.h +++ b/include/libxml/tree.h @@ -76,7 +76,8 @@ typedef enum { XML_BUFFER_ALLOC_EXACT, /* grow only to the minimal size */ XML_BUFFER_ALLOC_IMMUTABLE, /* immutable buffer */ XML_BUFFER_ALLOC_IO, /* special allocation scheme used for I/O */ - XML_BUFFER_ALLOC_HYBRID /* exact up to a threshold, and doubleit thereafter */ + XML_BUFFER_ALLOC_HYBRID, /* exact up to a threshold, and doubleit thereafter */ + XML_BUFFER_ALLOC_BOUNDED /* limit the upper size of the buffer */ } xmlBufferAllocationScheme; /** diff --git a/xmlreader.c b/xmlreader.c index f19e1233..471e7e2a 100644 --- a/xmlreader.c +++ b/xmlreader.c @@ -2091,6 +2091,9 @@ xmlNewTextReader(xmlParserInputBufferPtr input, const char *URI) { "xmlNewTextReader : malloc failed\n"); return(NULL); } + /* no operation on a reader should require a huge buffer */ + xmlBufSetAllocationScheme(ret->buffer, + XML_BUFFER_ALLOC_BOUNDED); ret->sax = (xmlSAXHandler *) xmlMalloc(sizeof(xmlSAXHandler)); if (ret->sax == NULL) { xmlBufFree(ret->buffer); @@ -3616,6 +3619,7 @@ xmlTextReaderConstValue(xmlTextReaderPtr reader) { return(((xmlNsPtr) node)->href); case XML_ATTRIBUTE_NODE:{ xmlAttrPtr attr = (xmlAttrPtr) node; + const xmlChar *ret; if ((attr->children != NULL) && (attr->children->type == XML_TEXT_NODE) && @@ -3629,10 +3633,21 @@ xmlTextReaderConstValue(xmlTextReaderPtr reader) { "xmlTextReaderSetup : malloc failed\n"); return (NULL); } + xmlBufSetAllocationScheme(reader->buffer, + XML_BUFFER_ALLOC_BOUNDED); } else xmlBufEmpty(reader->buffer); xmlBufGetNodeContent(reader->buffer, node); - return(xmlBufContent(reader->buffer)); + ret = xmlBufContent(reader->buffer); + if (ret == NULL) { + /* error on the buffer best to reallocate */ + xmlBufFree(reader->buffer); + reader->buffer = xmlBufCreateSize(100); + xmlBufSetAllocationScheme(reader->buffer, + XML_BUFFER_ALLOC_BOUNDED); + ret = BAD_CAST ""; + } + return(ret); } break; } @@ -5131,6 +5146,9 @@ xmlTextReaderSetup(xmlTextReaderPtr reader, "xmlTextReaderSetup : malloc failed\n"); return (-1); } + /* no operation on a reader should require a huge buffer */ + xmlBufSetAllocationScheme(reader->buffer, + XML_BUFFER_ALLOC_BOUNDED); if (reader->sax == NULL) reader->sax = (xmlSAXHandler *) xmlMalloc(sizeof(xmlSAXHandler)); if (reader->sax == NULL) { |