[Buildroot] [PATCH] package/x11r7/xserver_xorg-server: add upstream security fixes for CVE-2020-14360 / 25712

Peter Korsgaard peter at korsgaard.com
Tue Dec 1 17:49:03 UTC 2020


Fixes the following security issues:

* CVE-2020-14360 / ZDI CAN 11572 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.

* CVE-2020-25712 / ZDI-CAN-11839 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.

For more details, see the advisory:
https://www.openwall.com/lists/oss-security/2020/12/01/3

Signed-off-by: Peter Korsgaard <peter at korsgaard.com>
---
 ...Info-and-SetDeviceIndicators-heap-ov.patch | 100 +++++++++++++
 ...heck-SetMap-request-length-carefully.patch | 131 ++++++++++++++++++
 2 files changed, 231 insertions(+)
 create mode 100644 package/x11r7/xserver_xorg-server/0007-Fix-XkbSetDeviceInfo-and-SetDeviceIndicators-heap-ov.patch
 create mode 100644 package/x11r7/xserver_xorg-server/0008-Check-SetMap-request-length-carefully.patch

diff --git a/package/x11r7/xserver_xorg-server/0007-Fix-XkbSetDeviceInfo-and-SetDeviceIndicators-heap-ov.patch b/package/x11r7/xserver_xorg-server/0007-Fix-XkbSetDeviceInfo-and-SetDeviceIndicators-heap-ov.patch
new file mode 100644
index 0000000000..8297aa8a9f
--- /dev/null
+++ b/package/x11r7/xserver_xorg-server/0007-Fix-XkbSetDeviceInfo-and-SetDeviceIndicators-heap-ov.patch
@@ -0,0 +1,100 @@
+From 87c64fc5b0db9f62f4e361444f4b60501ebf67b9 Mon Sep 17 00:00:00 2001
+From: Matthieu Herrb <matthieu at herrb.eu>
+Date: Sun, 11 Oct 2020 17:05:09 +0200
+Subject: [PATCH] Fix XkbSetDeviceInfo() and SetDeviceIndicators() heap
+ overflows
+
+ZDI-CAN 11389 / CVE-2020-25712
+
+This vulnerability was discovered by:
+Jan-Niklas Sohn working with Trend Micro Zero Day Initiative
+
+Signed-off-by: Matthieu Herrb <matthieu at herrb.eu>
+Signed-off-by: Peter Korsgaard <peter at korsgaard.com>
+---
+ xkb/xkb.c | 26 +++++++++++++++++++++++---
+ 1 file changed, 23 insertions(+), 3 deletions(-)
+
+diff --git a/xkb/xkb.c b/xkb/xkb.c
+index 8e016cd74..f54cc97f8 100644
+--- a/xkb/xkb.c
++++ b/xkb/xkb.c
+@@ -6536,7 +6536,9 @@ SetDeviceIndicators(char *wire,
+                     unsigned changed,
+                     int num,
+                     int *status_rtrn,
+-                    ClientPtr client, xkbExtensionDeviceNotify * ev)
++                    ClientPtr client,
++                    xkbExtensionDeviceNotify * ev,
++                    xkbSetDeviceInfoReq * stuff)
+ {
+     xkbDeviceLedsWireDesc *ledWire;
+     int i;
+@@ -6557,6 +6559,11 @@ SetDeviceIndicators(char *wire,
+         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);
+@@ -6575,6 +6582,10 @@ SetDeviceIndicators(char *wire,
+             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;
+@@ -6592,6 +6603,10 @@ SetDeviceIndicators(char *wire,
+         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;
+@@ -6671,7 +6686,7 @@ _XkbSetDeviceInfoCheck(ClientPtr client, DeviceIntPtr dev,
+     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;
+ 
+@@ -6683,7 +6698,11 @@ _XkbSetDeviceInfoCheck(ClientPtr client, DeviceIntPtr dev,
+                 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;
+@@ -6704,7 +6723,8 @@ _XkbSetDeviceInfoCheck(ClientPtr client, DeviceIntPtr dev,
+         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;
+     }
+-- 
+2.20.1
+
diff --git a/package/x11r7/xserver_xorg-server/0008-Check-SetMap-request-length-carefully.patch b/package/x11r7/xserver_xorg-server/0008-Check-SetMap-request-length-carefully.patch
new file mode 100644
index 0000000000..a8b33ebf3b
--- /dev/null
+++ b/package/x11r7/xserver_xorg-server/0008-Check-SetMap-request-length-carefully.patch
@@ -0,0 +1,131 @@
+From 446ff2d3177087b8173fa779fa5b77a2a128988b Mon Sep 17 00:00:00 2001
+From: Matthieu Herrb <matthieu at herrb.eu>
+Date: Thu, 12 Nov 2020 19:15:07 +0100
+Subject: [PATCH] Check SetMap request length carefully.
+
+Avoid out of bounds memory accesses on too short request.
+
+ZDI-CAN 11572 /  CVE-2020-14360
+
+This vulnerability was discovered by:
+Jan-Niklas Sohn working with Trend Micro Zero Day Initiative
+
+Signed-off-by: Matthieu Herrb <matthieu at herrb.eu>
+Signed-off-by: Peter Korsgaard <peter at korsgaard.com>
+---
+ xkb/xkb.c | 92 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
+ 1 file changed, 92 insertions(+)
+
+diff --git a/xkb/xkb.c b/xkb/xkb.c
+index f54cc97f8..d056c698c 100644
+--- a/xkb/xkb.c
++++ b/xkb/xkb.c
+@@ -2382,6 +2382,93 @@ SetVirtualModMap(XkbSrvInfoPtr xkbi,
+     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, except swap values when client->swapped and doswap are both true.
+@@ -2642,6 +2729,11 @@ ProcXkbSetMap(ClientPtr client)
+     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
+-- 
+2.20.1
+
-- 
2.20.1



More information about the buildroot mailing list