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[CVE-2022-29824] Fix integer overflows in xmlBuf and xmlBuffer

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In several places, the code handling string buffers didn't check for
integer overflow or used wrong types for buffer sizes. This could
result in out-of-bounds writes or other memory errors when working on
large, multi-gigabyte buffers.

Thanks to Felix Wilhelm for the report.
This commit is contained in:
Nick Wellnhofer 2022-03-08 20:10:02 +01:00
parent 433b318668
commit 6c283d83ec
2 changed files with 60 additions and 96 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

84
buf.c
View File

@ -26,6 +26,10 @@
#include <libxml/parserInternals.h> /* for XML_MAX_TEXT_LENGTH */
#include "buf.h"
#ifndef SIZE_MAX
#define SIZE_MAX ((size_t) -1)
#endif
#define WITH_BUFFER_COMPAT
/**
@ -151,6 +155,8 @@ xmlBufPtr
xmlBufCreateSize(size_t size) {
xmlBufPtr ret;
if (size == SIZE_MAX)
return(NULL);
ret = (xmlBufPtr) xmlMalloc(sizeof(xmlBuf));
if (ret == NULL) {
xmlBufMemoryError(NULL, "creating buffer");
@ -160,7 +166,7 @@ xmlBufCreateSize(size_t size) {
ret->error = 0;
ret->buffer = NULL;
ret->alloc = xmlBufferAllocScheme;
ret->size = (size ? size+2 : 0); /* +1 for ending null */
ret->size = (size ? size + 1 : 0); /* +1 for ending null */
UPDATE_COMPAT(ret);
if (ret->size){
ret->content = (xmlChar *) xmlMallocAtomic(ret->size * sizeof(xmlChar));
@ -429,23 +435,17 @@ xmlBufGrowInternal(xmlBufPtr buf, size_t len) {
CHECK_COMPAT(buf)
if (buf->alloc == XML_BUFFER_ALLOC_IMMUTABLE) return(0);
if (buf->use + len < buf->size)
if (len < buf->size - buf->use)
return(buf->size - buf->use);
if (len > SIZE_MAX - buf->use)
return(0);
/*
* Windows has a BIG problem on realloc timing, so we try to double
* the buffer size (if that's enough) (bug 146697)
* Apparently BSD too, and it's probably best for linux too
* On an embedded system this may be something to change
*/
#if 1
if (buf->size > (size_t) len)
size = buf->size * 2;
else
size = buf->use + len + 100;
#else
size = buf->use + len + 100;
#endif
if (buf->size > (size_t) len) {
size = buf->size > SIZE_MAX / 2 ? SIZE_MAX : buf->size * 2;
} else {
size = buf->use + len;
size = size > SIZE_MAX - 100 ? SIZE_MAX : size + 100;
}
if (buf->alloc == XML_BUFFER_ALLOC_BOUNDED) {
/*
@ -731,7 +731,7 @@ xmlBufIsEmpty(const xmlBufPtr buf)
int
xmlBufResize(xmlBufPtr buf, size_t size)
{
unsigned int newSize;
size_t newSize;
xmlChar* rebuf = NULL;
size_t start_buf;
@ -759,9 +759,13 @@ xmlBufResize(xmlBufPtr buf, size_t size)
case XML_BUFFER_ALLOC_IO:
case XML_BUFFER_ALLOC_DOUBLEIT:
/*take care of empty case*/
newSize = (buf->size ? buf->size*2 : size + 10);
if (buf->size == 0) {
newSize = (size > SIZE_MAX - 10 ? SIZE_MAX : size + 10);
} else {
newSize = buf->size;
}
while (size > newSize) {
if (newSize > UINT_MAX / 2) {
if (newSize > SIZE_MAX / 2) {
xmlBufMemoryError(buf, "growing buffer");
return 0;
}
@ -769,15 +773,15 @@ xmlBufResize(xmlBufPtr buf, size_t size)
}
break;
case XML_BUFFER_ALLOC_EXACT:
newSize = size+10;
newSize = (size > SIZE_MAX - 10 ? SIZE_MAX : size + 10);
break;
case XML_BUFFER_ALLOC_HYBRID:
if (buf->use < BASE_BUFFER_SIZE)
newSize = size;
else {
newSize = buf->size * 2;
newSize = buf->size;
while (size > newSize) {
if (newSize > UINT_MAX / 2) {
if (newSize > SIZE_MAX / 2) {
xmlBufMemoryError(buf, "growing buffer");
return 0;
}
@ -787,7 +791,7 @@ xmlBufResize(xmlBufPtr buf, size_t size)
break;
default:
newSize = size+10;
newSize = (size > SIZE_MAX - 10 ? SIZE_MAX : size + 10);
break;
}
@ -853,7 +857,7 @@ xmlBufResize(xmlBufPtr buf, size_t size)
*/
int
xmlBufAdd(xmlBufPtr buf, const xmlChar *str, int len) {
unsigned int needSize;
size_t needSize;
if ((str == NULL) || (buf == NULL) || (buf->error))
return -1;
@ -875,8 +879,10 @@ xmlBufAdd(xmlBufPtr buf, const xmlChar *str, int len) {
if (len < 0) return -1;
if (len == 0) return 0;
needSize = buf->use + len + 2;
if (needSize > buf->size){
if ((size_t) len >= buf->size - buf->use) {
if ((size_t) len >= SIZE_MAX - buf->use)
return(-1);
needSize = buf->use + len + 1;
if (buf->alloc == XML_BUFFER_ALLOC_BOUNDED) {
/*
* Used to provide parsing limits
@ -1012,31 +1018,7 @@ xmlBufCat(xmlBufPtr buf, const xmlChar *str) {
*/
int
xmlBufCCat(xmlBufPtr buf, const char *str) {
const char *cur;
if ((buf == NULL) || (buf->error))
return(-1);
CHECK_COMPAT(buf)
if (buf->alloc == XML_BUFFER_ALLOC_IMMUTABLE) return -1;
if (str == NULL) {
#ifdef DEBUG_BUFFER
xmlGenericError(xmlGenericErrorContext,
"xmlBufCCat: str == NULL\n");
#endif
return -1;
}
for (cur = str;*cur != 0;cur++) {
if (buf->use + 10 >= buf->size) {
if (!xmlBufResize(buf, buf->use+10)){
xmlBufMemoryError(buf, "growing buffer");
return XML_ERR_NO_MEMORY;
}
}
buf->content[buf->use++] = *cur;
}
buf->content[buf->use] = 0;
UPDATE_COMPAT(buf)
return 0;
return xmlBufCat(buf, (const xmlChar *) str);
}
/**

72
tree.c
View File

@ -7120,6 +7120,8 @@ xmlBufferPtr
xmlBufferCreateSize(size_t size) {
xmlBufferPtr ret;
if (size >= UINT_MAX)
return(NULL);
ret = (xmlBufferPtr) xmlMalloc(sizeof(xmlBuffer));
if (ret == NULL) {
xmlTreeErrMemory("creating buffer");
@ -7127,7 +7129,7 @@ xmlBufferCreateSize(size_t size) {
}
ret->use = 0;
ret->alloc = xmlBufferAllocScheme;
ret->size = (size ? size+2 : 0); /* +1 for ending null */
ret->size = (size ? size + 1 : 0); /* +1 for ending null */
if (ret->size){
ret->content = (xmlChar *) xmlMallocAtomic(ret->size * sizeof(xmlChar));
if (ret->content == NULL) {
@ -7187,6 +7189,8 @@ xmlBufferCreateStatic(void *mem, size_t size) {
if ((mem == NULL) || (size == 0))
return(NULL);
if (size > UINT_MAX)
return(NULL);
ret = (xmlBufferPtr) xmlMalloc(sizeof(xmlBuffer));
if (ret == NULL) {
@ -7334,28 +7338,23 @@ xmlBufferShrink(xmlBufferPtr buf, unsigned int len) {
*/
int
xmlBufferGrow(xmlBufferPtr buf, unsigned int len) {
int size;
unsigned int size;
xmlChar *newbuf;
if (buf == NULL) return(-1);
if (buf->alloc == XML_BUFFER_ALLOC_IMMUTABLE) return(0);
if (len + buf->use < buf->size) return(0);
if (len < buf->size - buf->use)
return(0);
if (len > UINT_MAX - buf->use)
return(-1);
/*
* Windows has a BIG problem on realloc timing, so we try to double
* the buffer size (if that's enough) (bug 146697)
* Apparently BSD too, and it's probably best for linux too
* On an embedded system this may be something to change
*/
#if 1
if (buf->size > len)
size = buf->size * 2;
else
size = buf->use + len + 100;
#else
size = buf->use + len + 100;
#endif
if (buf->size > (size_t) len) {
size = buf->size > UINT_MAX / 2 ? UINT_MAX : buf->size * 2;
} else {
size = buf->use + len;
size = size > UINT_MAX - 100 ? UINT_MAX : size + 100;
}
if ((buf->alloc == XML_BUFFER_ALLOC_IO) && (buf->contentIO != NULL)) {
size_t start_buf = buf->content - buf->contentIO;
@ -7482,7 +7481,10 @@ xmlBufferResize(xmlBufferPtr buf, unsigned int size)
case XML_BUFFER_ALLOC_IO:
case XML_BUFFER_ALLOC_DOUBLEIT:
/*take care of empty case*/
newSize = (buf->size ? buf->size : size + 10);
if (buf->size == 0)
newSize = (size > UINT_MAX - 10 ? UINT_MAX : size + 10);
else
newSize = buf->size;
while (size > newSize) {
if (newSize > UINT_MAX / 2) {
xmlTreeErrMemory("growing buffer");
@ -7492,7 +7494,7 @@ xmlBufferResize(xmlBufferPtr buf, unsigned int size)
}
break;
case XML_BUFFER_ALLOC_EXACT:
newSize = size+10;
newSize = (size > UINT_MAX - 10 ? UINT_MAX : size + 10);;
break;
case XML_BUFFER_ALLOC_HYBRID:
if (buf->use < BASE_BUFFER_SIZE)
@ -7510,7 +7512,7 @@ xmlBufferResize(xmlBufferPtr buf, unsigned int size)
break;
default:
newSize = size+10;
newSize = (size > UINT_MAX - 10 ? UINT_MAX : size + 10);;
break;
}
@ -7596,8 +7598,10 @@ xmlBufferAdd(xmlBufferPtr buf, const xmlChar *str, int len) {
if (len < 0) return -1;
if (len == 0) return 0;
needSize = buf->use + len + 2;
if (needSize > buf->size){
if ((unsigned) len >= buf->size - buf->use) {
if ((unsigned) len >= UINT_MAX - buf->use)
return XML_ERR_NO_MEMORY;
needSize = buf->use + len + 1;
if (!xmlBufferResize(buf, needSize)){
xmlTreeErrMemory("growing buffer");
return XML_ERR_NO_MEMORY;
@ -7710,29 +7714,7 @@ xmlBufferCat(xmlBufferPtr buf, const xmlChar *str) {
*/
int
xmlBufferCCat(xmlBufferPtr buf, const char *str) {
const char *cur;
if (buf == NULL)
return(-1);
if (buf->alloc == XML_BUFFER_ALLOC_IMMUTABLE) return -1;
if (str == NULL) {
#ifdef DEBUG_BUFFER
xmlGenericError(xmlGenericErrorContext,
"xmlBufferCCat: str == NULL\n");
#endif
return -1;
}
for (cur = str;*cur != 0;cur++) {
if (buf->use + 10 >= buf->size) {
if (!xmlBufferResize(buf, buf->use+10)){
xmlTreeErrMemory("growing buffer");
return XML_ERR_NO_MEMORY;
}
}
buf->content[buf->use++] = *cur;
}
buf->content[buf->use] = 0;
return 0;
return xmlBufferCat(buf, (const xmlChar *) str);
}
/**