Bug#976216: xorg-server: CVE-2020-25712 CVE-2020-14360
Hi,
On Tue, Dec 01, 2020 at 05:58:56PM +0100, Salvatore Bonaccorso wrote:
> The following vulnerabilities were published for xorg-server.
>
> CVE-2020-25712[0]:
> | Fix XkbSetDeviceInfo() and SetDeviceIndicators() heap overflows
>
> CVE-2020-14360[1]:
> | Check SetMap request length carefully
>
> If you fix the vulnerabilities please also make sure to include the
> CVE (Common Vulnerabilities & Exposures) ids in your changelog entry.
>
I'm assuming we'll want this in buster-security?
Proposed patch below, it's a clean cherry-pick from server-1.20-branch;
Timo's working on updating sid to 1.20.10. This being xkb I'd prefer to
wait a couple of days to watch out for any regressions before shipping
the update in stable if possible, but we can get started with an upload
and builds right away.
Cheers,
Julien
diff -u xorg-server-1.20.4/debian/changelog xorg-server-1.20.4/debian/changelog
--- xorg-server-1.20.4/debian/changelog
+++ xorg-server-1.20.4/debian/changelog
@@ -1,3 +1,15 @@
+xorg-server (2:1.20.4-1+deb10u2) buster-security; urgency=high
+
+ * Team upload.
+ * Security fixes from
+ https://lists.x.org/archives/xorg-announce/2020-December/003066.html
+ (closes: #976216)
+ * Fix XkbSetDeviceInfo() and SetDeviceIndicators() heap overflows
+ (CVE-2020-25712)
+ * Check SetMap request length carefully (CVE-2020-14360)
+
+ -- Julien Cristau <jcristau@debian.org> Wed, 02 Dec 2020 11:39:24 +0100
+
xorg-server (2:1.20.4-1+deb10u1) buster-security; urgency=high
* Non-maintainer upload by the Security Team.
only in patch2:
unchanged:
--- xorg-server-1.20.4.orig/xkb/xkb.c
+++ xorg-server-1.20.4/xkb/xkb.c
@@ -2366,6 +2366,93 @@
return (char *) wire;
}
+#define _add_check_len(new) \
+ if (len > UINT32_MAX - (new) || len > req_len - (new)) goto bad; \
+ else len += new
+
+/**
+ * Check the length of the SetMap request
+ */
+static int
+_XkbSetMapCheckLength(xkbSetMapReq *req)
+{
+ size_t len = sz_xkbSetMapReq, req_len = req->length << 2;
+ xkbKeyTypeWireDesc *keytype;
+ xkbSymMapWireDesc *symmap;
+ BOOL preserve;
+ int i, map_count, nSyms;
+
+ if (req_len < len)
+ goto bad;
+ /* types */
+ if (req->present & XkbKeyTypesMask) {
+ keytype = (xkbKeyTypeWireDesc *)(req + 1);
+ for (i = 0; i < req->nTypes; i++) {
+ _add_check_len(XkbPaddedSize(sz_xkbKeyTypeWireDesc));
+ if (req->flags & XkbSetMapResizeTypes) {
+ _add_check_len(keytype->nMapEntries
+ * sz_xkbKTSetMapEntryWireDesc);
+ preserve = keytype->preserve;
+ map_count = keytype->nMapEntries;
+ if (preserve) {
+ _add_check_len(map_count * sz_xkbModsWireDesc);
+ }
+ keytype += 1;
+ keytype = (xkbKeyTypeWireDesc *)
+ ((xkbKTSetMapEntryWireDesc *)keytype + map_count);
+ if (preserve)
+ keytype = (xkbKeyTypeWireDesc *)
+ ((xkbModsWireDesc *)keytype + map_count);
+ }
+ }
+ }
+ /* syms */
+ if (req->present & XkbKeySymsMask) {
+ symmap = (xkbSymMapWireDesc *)((char *)req + len);
+ for (i = 0; i < req->nKeySyms; i++) {
+ _add_check_len(sz_xkbSymMapWireDesc);
+ nSyms = symmap->nSyms;
+ _add_check_len(nSyms*sizeof(CARD32));
+ symmap += 1;
+ symmap = (xkbSymMapWireDesc *)((CARD32 *)symmap + nSyms);
+ }
+ }
+ /* actions */
+ if (req->present & XkbKeyActionsMask) {
+ _add_check_len(req->totalActs * sz_xkbActionWireDesc
+ + XkbPaddedSize(req->nKeyActs));
+ }
+ /* behaviours */
+ if (req->present & XkbKeyBehaviorsMask) {
+ _add_check_len(req->totalKeyBehaviors * sz_xkbBehaviorWireDesc);
+ }
+ /* vmods */
+ if (req->present & XkbVirtualModsMask) {
+ _add_check_len(XkbPaddedSize(Ones(req->virtualMods)));
+ }
+ /* explicit */
+ if (req->present & XkbExplicitComponentsMask) {
+ /* two bytes per non-zero explicit componen */
+ _add_check_len(XkbPaddedSize(req->totalKeyExplicit * sizeof(CARD16)));
+ }
+ /* modmap */
+ if (req->present & XkbModifierMapMask) {
+ /* two bytes per non-zero modmap component */
+ _add_check_len(XkbPaddedSize(req->totalModMapKeys * sizeof(CARD16)));
+ }
+ /* vmodmap */
+ if (req->present & XkbVirtualModMapMask) {
+ _add_check_len(req->totalVModMapKeys * sz_xkbVModMapWireDesc);
+ }
+ if (len == req_len)
+ return Success;
+bad:
+ ErrorF("[xkb] BOGUS LENGTH in SetMap: expected %ld got %ld\n",
+ len, req_len);
+ return BadLength;
+}
+
+
/**
* Check if the given request can be applied to the given device but don't
* actually do anything..
@@ -2617,6 +2704,11 @@
CHK_KBD_DEVICE(dev, stuff->deviceSpec, client, DixManageAccess);
CHK_MASK_LEGAL(0x01, stuff->present, XkbAllMapComponentsMask);
+ /* first verify the request length carefully */
+ rc = _XkbSetMapCheckLength(stuff);
+ if (rc != Success)
+ return rc;
+
tmp = (char *) &stuff[1];
/* Check if we can to the SetMap on the requested device. If this
@@ -6476,7 +6568,9 @@
unsigned changed,
int num,
int *status_rtrn,
- ClientPtr client, xkbExtensionDeviceNotify * ev)
+ ClientPtr client,
+ xkbExtensionDeviceNotify * ev,
+ xkbSetDeviceInfoReq * stuff)
{
xkbDeviceLedsWireDesc *ledWire;
int i;
@@ -6497,6 +6591,11 @@
xkbIndicatorMapWireDesc *mapWire;
XkbSrvLedInfoPtr sli;
+ if (!_XkbCheckRequestBounds(client, stuff, ledWire, ledWire + 1)) {
+ *status_rtrn = BadLength;
+ return (char *) ledWire;
+ }
+
namec = mapc = statec = 0;
sli = XkbFindSrvLedInfo(dev, ledWire->ledClass, ledWire->ledID,
XkbXI_IndicatorMapsMask);
@@ -6515,6 +6614,10 @@
memset((char *) sli->names, 0, XkbNumIndicators * sizeof(Atom));
for (n = 0, bit = 1; n < XkbNumIndicators; n++, bit <<= 1) {
if (ledWire->namesPresent & bit) {
+ if (!_XkbCheckRequestBounds(client, stuff, atomWire, atomWire + 1)) {
+ *status_rtrn = BadLength;
+ return (char *) atomWire;
+ }
sli->names[n] = (Atom) *atomWire;
if (sli->names[n] == None)
ledWire->namesPresent &= ~bit;
@@ -6532,6 +6635,10 @@
if (ledWire->mapsPresent) {
for (n = 0, bit = 1; n < XkbNumIndicators; n++, bit <<= 1) {
if (ledWire->mapsPresent & bit) {
+ if (!_XkbCheckRequestBounds(client, stuff, mapWire, mapWire + 1)) {
+ *status_rtrn = BadLength;
+ return (char *) mapWire;
+ }
sli->maps[n].flags = mapWire->flags;
sli->maps[n].which_groups = mapWire->whichGroups;
sli->maps[n].groups = mapWire->groups;
@@ -6611,7 +6718,7 @@
ed.deviceID = dev->id;
wire = (char *) &stuff[1];
if (stuff->change & XkbXI_ButtonActionsMask) {
- int nBtns, sz, i;
+ int nBtns, sz, i;
XkbAction *acts;
DeviceIntPtr kbd;
@@ -6623,7 +6730,11 @@
return BadAlloc;
dev->button->xkb_acts = acts;
}
+ if (stuff->firstBtn + stuff->nBtns > nBtns)
+ return BadValue;
sz = stuff->nBtns * SIZEOF(xkbActionWireDesc);
+ if (!_XkbCheckRequestBounds(client, stuff, wire, (char *) wire + sz))
+ return BadLength;
memcpy((char *) &acts[stuff->firstBtn], (char *) wire, sz);
wire += sz;
ed.reason |= XkbXI_ButtonActionsMask;
@@ -6644,7 +6755,8 @@
int status = Success;
wire = SetDeviceIndicators(wire, dev, stuff->change,
- stuff->nDeviceLedFBs, &status, client, &ed);
+ stuff->nDeviceLedFBs, &status, client, &ed,
+ stuff);
if (status != Success)
return status;
}
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