Stefan Dirsch
b8ff8cd1c1
* XkbSetMap Out-Of-Bounds Access: Insufficient checks on the
lengths of the XkbSetMap request can lead to out of bounds
memory accesses in the X server. (ZDI-CAN 11572,
CVE-2020-14360, bsc#1174908)
- U_Fix-XkbSetDeviceInfo-and-SetDeviceIndicators-heap-ov.patch
* XkbSetDeviceInfo Heap-based Buffer Overflow: Insufficient
checks on input of the XkbSetDeviceInfo request can lead to a
buffer overflow on the head in the X server. (ZDI-CAN 11389,
CVE-2020-25712, bsc#1177596)
OBS-URL: https://build.opensuse.org/package/show/X11:XOrg/xorg-x11-server?expand=0&rev=782
128 lines
4.3 KiB
Diff
128 lines
4.3 KiB
Diff
From 446ff2d3177087b8173fa779fa5b77a2a128988b Mon Sep 17 00:00:00 2001
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From: Matthieu Herrb <matthieu@herrb.eu>
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Date: Thu, 12 Nov 2020 19:15:07 +0100
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Subject: [PATCH] Check SetMap request length carefully.
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Avoid out of bounds memory accesses on too short request.
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ZDI-CAN 11572 / CVE-2020-14360
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This vulnerability was discovered by:
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Jan-Niklas Sohn working with Trend Micro Zero Day Initiative
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Signed-off-by: Matthieu Herrb <matthieu@herrb.eu>
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---
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xkb/xkb.c | 92 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
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1 file changed, 92 insertions(+)
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Index: xserver-1.20.9/xkb/xkb.c
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===================================================================
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--- xserver-1.20.9.orig/xkb/xkb.c
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+++ xserver-1.20.9/xkb/xkb.c
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@@ -2382,6 +2382,93 @@ SetVirtualModMap(XkbSrvInfoPtr xkbi,
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return (char *) wire;
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}
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+#define _add_check_len(new) \
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+ if (len > UINT32_MAX - (new) || len > req_len - (new)) goto bad; \
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+ else len += new
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+
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+/**
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+ * Check the length of the SetMap request
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+ */
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+static int
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+_XkbSetMapCheckLength(xkbSetMapReq *req)
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+{
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+ size_t len = sz_xkbSetMapReq, req_len = req->length << 2;
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+ xkbKeyTypeWireDesc *keytype;
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+ xkbSymMapWireDesc *symmap;
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+ BOOL preserve;
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+ int i, map_count, nSyms;
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+
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+ if (req_len < len)
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+ goto bad;
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+ /* types */
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+ if (req->present & XkbKeyTypesMask) {
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+ keytype = (xkbKeyTypeWireDesc *)(req + 1);
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+ for (i = 0; i < req->nTypes; i++) {
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+ _add_check_len(XkbPaddedSize(sz_xkbKeyTypeWireDesc));
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+ if (req->flags & XkbSetMapResizeTypes) {
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+ _add_check_len(keytype->nMapEntries
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+ * sz_xkbKTSetMapEntryWireDesc);
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+ preserve = keytype->preserve;
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+ map_count = keytype->nMapEntries;
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+ if (preserve) {
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+ _add_check_len(map_count * sz_xkbModsWireDesc);
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+ }
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+ keytype += 1;
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+ keytype = (xkbKeyTypeWireDesc *)
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+ ((xkbKTSetMapEntryWireDesc *)keytype + map_count);
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+ if (preserve)
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+ keytype = (xkbKeyTypeWireDesc *)
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+ ((xkbModsWireDesc *)keytype + map_count);
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+ }
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+ }
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+ }
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+ /* syms */
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+ if (req->present & XkbKeySymsMask) {
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+ symmap = (xkbSymMapWireDesc *)((char *)req + len);
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+ for (i = 0; i < req->nKeySyms; i++) {
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+ _add_check_len(sz_xkbSymMapWireDesc);
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+ nSyms = symmap->nSyms;
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+ _add_check_len(nSyms*sizeof(CARD32));
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+ symmap += 1;
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+ symmap = (xkbSymMapWireDesc *)((CARD32 *)symmap + nSyms);
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+ }
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+ }
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+ /* actions */
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+ if (req->present & XkbKeyActionsMask) {
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+ _add_check_len(req->totalActs * sz_xkbActionWireDesc
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+ + XkbPaddedSize(req->nKeyActs));
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+ }
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+ /* behaviours */
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+ if (req->present & XkbKeyBehaviorsMask) {
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+ _add_check_len(req->totalKeyBehaviors * sz_xkbBehaviorWireDesc);
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+ }
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+ /* vmods */
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+ if (req->present & XkbVirtualModsMask) {
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+ _add_check_len(XkbPaddedSize(Ones(req->virtualMods)));
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+ }
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+ /* explicit */
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+ if (req->present & XkbExplicitComponentsMask) {
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+ /* two bytes per non-zero explicit componen */
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+ _add_check_len(XkbPaddedSize(req->totalKeyExplicit * sizeof(CARD16)));
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+ }
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+ /* modmap */
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+ if (req->present & XkbModifierMapMask) {
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+ /* two bytes per non-zero modmap component */
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+ _add_check_len(XkbPaddedSize(req->totalModMapKeys * sizeof(CARD16)));
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+ }
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+ /* vmodmap */
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+ if (req->present & XkbVirtualModMapMask) {
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+ _add_check_len(req->totalVModMapKeys * sz_xkbVModMapWireDesc);
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+ }
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+ if (len == req_len)
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+ return Success;
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+bad:
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+ ErrorF("[xkb] BOGUS LENGTH in SetMap: expected %ld got %ld\n",
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+ len, req_len);
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+ return BadLength;
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+}
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+
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+
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/**
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* Check if the given request can be applied to the given device but don't
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* actually do anything..
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@@ -2639,6 +2726,11 @@ ProcXkbSetMap(ClientPtr client)
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CHK_KBD_DEVICE(dev, stuff->deviceSpec, client, DixManageAccess);
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CHK_MASK_LEGAL(0x01, stuff->present, XkbAllMapComponentsMask);
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+ /* first verify the request length carefully */
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+ rc = _XkbSetMapCheckLength(stuff);
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+ if (rc != Success)
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+ return rc;
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+
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tmp = (char *) &stuff[1];
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/* Check if we can to the SetMap on the requested device. If this
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