From 5cec67e3f8d56e6e5fda2f90e102950cbb09e3d1 Mon Sep 17 00:00:00 2001 From: Daniel Veillard Date: Tue, 14 Apr 2015 17:41:48 +0800 Subject: [PATCH] CVE-2015-1819 Enforce the reader to run in constant memory To: libvir-list@redhat.com 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. Signed-off-by: Daniel Veillard --- buf.c | 43 ++++++++++++++++++++++++++++++++++++++++++- include/libxml/tree.h | 3 ++- xmlreader.c | 20 +++++++++++++++++++- 3 files changed, 63 insertions(+), 3 deletions(-) diff --git a/buf.c b/buf.c index d1756c4..b52e41d 100644 --- a/buf.c +++ b/buf.c @@ -27,6 +27,7 @@ #include #include #include +#include /* 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 7e06686..d904a44 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 00083d0..4fabaa9 100644 --- a/xmlreader.c +++ b/xmlreader.c @@ -2077,6 +2077,9 @@ 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); @@ -3602,6 +3605,7 @@ 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) && @@ -3615,10 +3619,21 @@ 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; } @@ -5117,6 +5132,9 @@ 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) { -- 2.5.0