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libvncserver: add security patches

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Fixes:
CVE-2014-6051 and
CVE-2014-6052 denial of service and possible code execution via
integer overflow and lack of malloc error handling in
MallocFrameBuffer()
CVE-2014-6053 denial of service via large ClientCutText message.
CVE-2014-6054 denial of service via zero scaling factor.
CVE-2014-6055 denial of service and possible code execution via
stack overflows in File Transfer feature.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
This commit is contained in:
Gustavo Zacarias 2014-09-30 20:12:54 -03:00 committed by Peter Korsgaard
parent 6018b55185
commit 4afb8cbad7
4 changed files with 343 additions and 0 deletions
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85
package/libvncserver/libvncserver-0001-CVE-2014-6051-6052.patch Normal file
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@ -0,0 +1,85 @@
Description: fix denial of service and possible code execution via
integer overflow and lack of malloc error handling in MallocFrameBuffer()
Origin: backport, https://github.com/newsoft/libvncserver/commit/045a044e8ae79db9244593fbce154cdf6e843273
Origin: backport, https://github.com/newsoft/libvncserver/commit/85a778c0e45e87e35ee7199f1f25020648e8b812
Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Index: libvncserver-0.9.9+dfsg/libvncclient/rfbproto.c
===================================================================
--- libvncserver-0.9.9+dfsg.orig/libvncclient/rfbproto.c 2012-05-04 10:19:00.000000000 -0400
+++ libvncserver-0.9.9+dfsg/libvncclient/rfbproto.c 2014-09-25 11:11:55.884057336 -0400
@@ -1807,7 +1807,8 @@
client->updateRect.x = client->updateRect.y = 0;
client->updateRect.w = client->width;
client->updateRect.h = client->height;
- client->MallocFrameBuffer(client);
+ if (!client->MallocFrameBuffer(client))
+ return FALSE;
SendFramebufferUpdateRequest(client, 0, 0, rect.r.w, rect.r.h, FALSE);
rfbClientLog("Got new framebuffer size: %dx%d\n", rect.r.w, rect.r.h);
continue;
@@ -2260,7 +2261,8 @@
client->updateRect.x = client->updateRect.y = 0;
client->updateRect.w = client->width;
client->updateRect.h = client->height;
- client->MallocFrameBuffer(client);
+ if (!client->MallocFrameBuffer(client))
+ return FALSE;
SendFramebufferUpdateRequest(client, 0, 0, client->width, client->height, FALSE);
rfbClientLog("Got new framebuffer size: %dx%d\n", client->width, client->height);
break;
@@ -2276,7 +2278,9 @@
client->updateRect.x = client->updateRect.y = 0;
client->updateRect.w = client->width;
client->updateRect.h = client->height;
- client->MallocFrameBuffer(client);
+ if (!client->MallocFrameBuffer(client))
+ return FALSE;
+
SendFramebufferUpdateRequest(client, 0, 0, client->width, client->height, FALSE);
rfbClientLog("Got new framebuffer size: %dx%d\n", client->width, client->height);
break;
Index: libvncserver-0.9.9+dfsg/libvncclient/vncviewer.c
===================================================================
--- libvncserver-0.9.9+dfsg.orig/libvncclient/vncviewer.c 2012-05-04 10:19:00.000000000 -0400
+++ libvncserver-0.9.9+dfsg/libvncclient/vncviewer.c 2014-09-25 11:10:29.984055035 -0400
@@ -82,9 +82,27 @@
#endif
}
static rfbBool MallocFrameBuffer(rfbClient* client) {
+uint64_t allocSize;
+
if(client->frameBuffer)
free(client->frameBuffer);
- client->frameBuffer=malloc(client->width*client->height*client->format.bitsPerPixel/8);
+
+ /* SECURITY: promote 'width' into uint64_t so that the multiplication does not overflow
+ 'width' and 'height' are 16-bit integers per RFB protocol design
+ SIZE_MAX is the maximum value that can fit into size_t
+ */
+ allocSize = (uint64_t)client->width * client->height * client->format.bitsPerPixel/8;
+
+ if (allocSize >= SIZE_MAX) {
+ rfbClientErr("CRITICAL: cannot allocate frameBuffer, requested size is too large\n");
+ return FALSE;
+ }
+
+ client->frameBuffer=malloc( (size_t)allocSize );
+
+ if (client->frameBuffer == NULL)
+ rfbClientErr("CRITICAL: frameBuffer allocation failed, requested size too large or not enough memory?\n");
+
return client->frameBuffer?TRUE:FALSE;
}
@@ -225,7 +243,8 @@
client->width=client->si.framebufferWidth;
client->height=client->si.framebufferHeight;
- client->MallocFrameBuffer(client);
+ if (!client->MallocFrameBuffer(client))
+ return FALSE;
if (!SetFormatAndEncodings(client))
return FALSE;

21
package/libvncserver/libvncserver-0002-CVE-2014-6053.patch Normal file
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@ -0,0 +1,21 @@
Description: fix denial of service via large ClientCutText message
Origin: backport, https://github.com/newsoft/libvncserver/commit/6037a9074d52b1963c97cb28ea1096c7c14cbf28
Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Index: libvncserver-0.9.9+dfsg/libvncserver/rfbserver.c
===================================================================
--- libvncserver-0.9.9+dfsg.orig/libvncserver/rfbserver.c 2012-05-04 10:19:00.000000000 -0400
+++ libvncserver-0.9.9+dfsg/libvncserver/rfbserver.c 2014-09-25 11:12:36.124058413 -0400
@@ -2457,6 +2457,11 @@
msg.cct.length = Swap32IfLE(msg.cct.length);
str = (char *)malloc(msg.cct.length);
+ if (str == NULL) {
+ rfbLogPerror("rfbProcessClientNormalMessage: not enough memory");
+ rfbCloseClient(cl);
+ return;
+ }
if ((n = rfbReadExact(cl, str, msg.cct.length)) <= 0) {
if (n != 0)

87
package/libvncserver/libvncserver-0003-CVE-2014-6054.patch Normal file
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@ -0,0 +1,87 @@
Description: fix denial of service via zero scaling factor
Origin: backport, https://github.com/newsoft/libvncserver/commit/05a9bd41a8ec0a9d580a8f420f41718bdd235446
Origin: backport, https://github.com/newsoft/libvncserver/commit/f18f24ce65f5cac22ddcf3ed51417e477f9bad09
Origin: backport, https://github.com/newsoft/libvncserver/commit/5dee1cbcd83920370a487c4fd2718aa4d3eba548
Origin: backport, https://github.com/newsoft/libvncserver/commit/819481c5e2003cd36d002336c248de8c75de362e
Origin: backport, https://github.com/newsoft/libvncserver/commit/e5d9b6a07257c12bf3b6242ddea79ea1c95353a8
Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Index: libvncserver-0.9.9+dfsg/libvncserver/rfbserver.c
===================================================================
--- libvncserver-0.9.9+dfsg.orig/libvncserver/rfbserver.c 2014-09-25 11:19:54.464070151 -0400
+++ libvncserver-0.9.9+dfsg/libvncserver/rfbserver.c 2014-09-25 11:20:04.344070416 -0400
@@ -2487,6 +2487,13 @@
rfbCloseClient(cl);
return;
}
+
+ if (msg.ssc.scale == 0) {
+ rfbLogPerror("rfbProcessClientNormalMessage: will not accept a scale factor of zero");
+ rfbCloseClient(cl);
+ return;
+ }
+
rfbStatRecordMessageRcvd(cl, msg.type, sz_rfbSetScaleMsg, sz_rfbSetScaleMsg);
rfbLog("rfbSetScale(%d)\n", msg.ssc.scale);
rfbScalingSetup(cl,cl->screen->width/msg.ssc.scale, cl->screen->height/msg.ssc.scale);
@@ -2503,6 +2510,13 @@
rfbCloseClient(cl);
return;
}
+
+ if (msg.ssc.scale == 0) {
+ rfbLogPerror("rfbProcessClientNormalMessage: will not accept a scale factor of zero");
+ rfbCloseClient(cl);
+ return;
+ }
+
rfbStatRecordMessageRcvd(cl, msg.type, sz_rfbSetScaleMsg, sz_rfbSetScaleMsg);
rfbLog("rfbSetScale(%d)\n", msg.ssc.scale);
rfbScalingSetup(cl,cl->screen->width/msg.ssc.scale, cl->screen->height/msg.ssc.scale);
Index: libvncserver-0.9.9+dfsg/libvncserver/scale.c
===================================================================
--- libvncserver-0.9.9+dfsg.orig/libvncserver/scale.c 2012-05-04 10:19:00.000000000 -0400
+++ libvncserver-0.9.9+dfsg/libvncserver/scale.c 2014-09-25 11:20:13.580070663 -0400
@@ -66,6 +66,10 @@
(double) ((int) (x)) : (double) ((int) (x) + 1) )
#define FLOOR(x) ( (double) ((int) (x)) )
+static inline int pad4(int value) {
+ int remainder = value & 3;
+ return value + (remainder == 0 ? 0 : 4 - remainder);
+}
int ScaleX(rfbScreenInfoPtr from, rfbScreenInfoPtr to, int x)
{
@@ -281,14 +285,29 @@
ptr = malloc(sizeof(rfbScreenInfo));
if (ptr!=NULL)
{
+ int allocSize;
+
/* copy *everything* (we don't use most of it, but just in case) */
memcpy(ptr, cl->screen, sizeof(rfbScreenInfo));
+
+ /* SECURITY: make sure that no integer overflow will occur afterwards.
+ * Note: this is defensive coding, as the check should have already been
+ * performed during initial, non-scaled screen setup.
+ */
+ allocSize = pad4(width * (ptr->bitsPerPixel/8)); /* per protocol, width<2**16 and bpp<256 */
+ if ((height == 0) || (allocSize >= (SIZE_MAX / height)))
+ {
+ free(ptr);
+ return NULL; /* malloc() will allocate an incorrect buffer size - early abort */
+ }
+
+ /* Resume copy everything */
ptr->width = width;
ptr->height = height;
ptr->paddedWidthInBytes = (ptr->bitsPerPixel/8)*ptr->width;
/* Need to by multiples of 4 for Sparc systems */
- ptr->paddedWidthInBytes += (ptr->paddedWidthInBytes % 4);
+ ptr->paddedWidthInBytes = pad4(ptr->paddedWidthInBytes);
/* Reset the reference count to 0! */
ptr->scaledScreenRefCount = 0;

150
package/libvncserver/libvncserver-0004-CVE-2014-6055.patch Normal file
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@ -0,0 +1,150 @@
Description: fix denial of service and possible code execution via
stack overflows in File Transfer feature
Origin: backport, https://github.com/newsoft/libvncserver/commit/06ccdf016154fde8eccb5355613ba04c59127b2e
Origin: backport, https://github.com/newsoft/libvncserver/commit/f528072216dec01cee7ca35d94e171a3b909e677
Origin: backport, https://github.com/newsoft/libvncserver/commit/256964b884c980038cd8b2f0d180fbb295b1c748
Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Index: libvncserver-0.9.9+dfsg/libvncserver/rfbserver.c
===================================================================
--- libvncserver-0.9.9+dfsg.orig/libvncserver/rfbserver.c 2014-09-25 11:20:22.972070915 -0400
+++ libvncserver-0.9.9+dfsg/libvncserver/rfbserver.c 2014-09-25 11:20:40.368071381 -0400
@@ -1237,21 +1237,35 @@
#define RFB_FILE_ATTRIBUTE_TEMPORARY 0x100
#define RFB_FILE_ATTRIBUTE_COMPRESSED 0x800
-rfbBool rfbFilenameTranslate2UNIX(rfbClientPtr cl, char *path, char *unixPath)
+rfbBool rfbFilenameTranslate2UNIX(rfbClientPtr cl, /* in */ char *path, /* out */ char *unixPath, size_t unixPathMaxLen )
{
int x;
char *home=NULL;
FILEXFER_ALLOWED_OR_CLOSE_AND_RETURN("", cl, FALSE);
+ /*
+ * Do not use strncpy() - truncating the file name would probably have undesirable side effects
+ * Instead check if destination buffer is big enough
+ */
+
+ if (strlen(path) >= unixPathMaxLen)
+ return FALSE;
+
/* C: */
if (path[0]=='C' && path[1]==':')
+ {
strcpy(unixPath, &path[2]);
+ }
else
{
home = getenv("HOME");
if (home!=NULL)
{
+ /* Re-check buffer size */
+ if ((strlen(path) + strlen(home) + 1) >= unixPathMaxLen)
+ return FALSE;
+
strcpy(unixPath, home);
strcat(unixPath,"/");
strcat(unixPath, path);
@@ -1289,7 +1303,8 @@
FILEXFER_ALLOWED_OR_CLOSE_AND_RETURN("", cl, FALSE);
/* Client thinks we are Winblows */
- rfbFilenameTranslate2UNIX(cl, buffer, path);
+ if (!rfbFilenameTranslate2UNIX(cl, buffer, path, sizeof(path)))
+ return FALSE;
if (DB) rfbLog("rfbProcessFileTransfer() rfbDirContentRequest: rfbRDirContent: \"%s\"->\"%s\"\n",buffer, path);
@@ -1566,7 +1581,9 @@
/* add some space to the end of the buffer as we will be adding a timespec to it */
if ((buffer = rfbProcessFileTransferReadBuffer(cl, length))==NULL) return FALSE;
/* The client requests a File */
- rfbFilenameTranslate2UNIX(cl, buffer, filename1);
+ if (!rfbFilenameTranslate2UNIX(cl, buffer, filename1, sizeof(filename1)))
+ goto fail;
+
cl->fileTransfer.fd=open(filename1, O_RDONLY, 0744);
/*
@@ -1660,16 +1677,17 @@
*/
if ((buffer = rfbProcessFileTransferReadBuffer(cl, length))==NULL) return FALSE;
- /* Parse the FileTime */
+ /* Parse the FileTime
+ * TODO: FileTime is actually never used afterwards
+ */
p = strrchr(buffer, ',');
if (p!=NULL) {
*p = '\0';
- strcpy(szFileTime, p+1);
+ strncpy(szFileTime, p+1, sizeof(szFileTime));
+ szFileTime[sizeof(szFileTime)-1] = '\x00'; /* ensure NULL terminating byte is present, even if copy overflowed */
} else
szFileTime[0]=0;
-
-
/* Need to read in sizeHtmp */
if ((n = rfbReadExact(cl, (char *)&sizeHtmp, 4)) <= 0) {
if (n != 0)
@@ -1681,7 +1699,8 @@
}
sizeHtmp = Swap32IfLE(sizeHtmp);
- rfbFilenameTranslate2UNIX(cl, buffer, filename1);
+ if (!rfbFilenameTranslate2UNIX(cl, buffer, filename1, sizeof(filename1)))
+ goto fail;
/* If the file exists... We can send a rfbFileChecksums back to the client before we send an rfbFileAcceptHeader */
/* TODO: Delta Transfer */
@@ -1810,7 +1829,9 @@
if ((buffer = rfbProcessFileTransferReadBuffer(cl, length))==NULL) return FALSE;
switch (contentParam) {
case rfbCDirCreate: /* Client requests the creation of a directory */
- rfbFilenameTranslate2UNIX(cl, buffer, filename1);
+ if (!rfbFilenameTranslate2UNIX(cl, buffer, filename1, sizeof(filename1)))
+ goto fail;
+
retval = mkdir(filename1, 0755);
if (DB) rfbLog("rfbProcessFileTransfer() rfbCommand: rfbCDirCreate(\"%s\"->\"%s\") %s\n", buffer, filename1, (retval==-1?"Failed":"Success"));
/*
@@ -1819,7 +1840,9 @@
if (buffer!=NULL) free(buffer);
return retval;
case rfbCFileDelete: /* Client requests the deletion of a file */
- rfbFilenameTranslate2UNIX(cl, buffer, filename1);
+ if (!rfbFilenameTranslate2UNIX(cl, buffer, filename1, sizeof(filename1)))
+ goto fail;
+
if (stat(filename1,&statbuf)==0)
{
if (S_ISDIR(statbuf.st_mode))
@@ -1837,8 +1860,12 @@
{
/* Split into 2 filenames ('*' is a seperator) */
*p = '\0';
- rfbFilenameTranslate2UNIX(cl, buffer, filename1);
- rfbFilenameTranslate2UNIX(cl, p+1, filename2);
+ if (!rfbFilenameTranslate2UNIX(cl, buffer, filename1, sizeof(filename1)))
+ goto fail;
+
+ if (!rfbFilenameTranslate2UNIX(cl, p+1, filename2, sizeof(filename2)))
+ goto fail;
+
retval = rename(filename1,filename2);
if (DB) rfbLog("rfbProcessFileTransfer() rfbCommand: rfbCFileRename(\"%s\"->\"%s\" -->> \"%s\"->\"%s\") %s\n", buffer, filename1, p+1, filename2, (retval==-1?"Failed":"Success"));
/*
@@ -1858,6 +1885,10 @@
/* NOTE: don't forget to free(buffer) if you return early! */
if (buffer!=NULL) free(buffer);
return TRUE;
+
+fail:
+ if (buffer!=NULL) free(buffer);
+ return FALSE;
}
/*