Xi: unvalidated lengths in Xinput extension [CVE-2014-8095]

Multiple functions in the Xinput extension handling of requests from
clients failed to check that the length of the request sent by the
client was large enough to perform all the required operations and
thus could read or write to memory outside the bounds of the request
buffer.

This commit includes the creation of a new REQUEST_AT_LEAST_EXTRA_SIZE
macro in include/dix.h for the common case of needing to ensure a
request is large enough to include both the request itself and a
minimum amount of extra data following the request header.

Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
(cherry picked from commit 73c63afb93c0af1bfd1969bf6e71c9edca586c77)
Signed-off-by: Julien Cristau <jcristau@debian.org>

17 files changed, 94 insertions, 18 deletions

diff --git a/Xi/chgdctl.c b/Xi/chgdctl.c
index d078aa248..b3ee867f0 100644
--- a/Xi/chgdctl.c
+++ b/Xi/chgdctl.c
@@ -78,7 +78,7 @@ SProcXChangeDeviceControl(ClientPtr client)
 
     REQUEST(xChangeDeviceControlReq);
     swaps(&stuff->length);
-    REQUEST_AT_LEAST_SIZE(xChangeDeviceControlReq);
+    REQUEST_AT_LEAST_EXTRA_SIZE(xChangeDeviceControlReq, sizeof(xDeviceCtl));
     swaps(&stuff->control);
     ctl = (xDeviceCtl *) &stuff[1];
     swaps(&ctl->control);
@@ -115,7 +115,7 @@ ProcXChangeDeviceControl(ClientPtr client)
     xDeviceEnableCtl *e;
 
     REQUEST(xChangeDeviceControlReq);
-    REQUEST_AT_LEAST_SIZE(xChangeDeviceControlReq);
+    REQUEST_AT_LEAST_EXTRA_SIZE(xChangeDeviceControlReq, sizeof(xDeviceCtl));
 
     len = stuff->length - bytes_to_int32(sizeof(xChangeDeviceControlReq));
     ret = dixLookupDevice(&dev, stuff->deviceid, client, DixManageAccess);
@@ -192,6 +192,10 @@ ProcXChangeDeviceControl(ClientPtr client)
         break;
     case DEVICE_ENABLE:
         e = (xDeviceEnableCtl *) &stuff[1];
+        if ((len != bytes_to_int32(sizeof(xDeviceEnableCtl)))) {
+            ret = BadLength;
+            goto out;
+        }
 
         if (IsXTestDevice(dev, NULL))
             status = !Success;
diff --git a/Xi/chgfctl.c b/Xi/chgfctl.c
index 6dcf60c66..224c2ba0a 100644
--- a/Xi/chgfctl.c
+++ b/Xi/chgfctl.c
@@ -467,6 +467,8 @@ ProcXChangeFeedbackControl(ClientPtr client)
         xStringFeedbackCtl *f = ((xStringFeedbackCtl *) &stuff[1]);
 
         if (client->swapped) {
+            if (len < bytes_to_int32(sizeof(xStringFeedbackCtl)))
+                return BadLength;
             swaps(&f->num_keysyms);
         }
         if (len !=
diff --git a/Xi/sendexev.c b/Xi/sendexev.c
index 3c213864b..183f88dae 100644
--- a/Xi/sendexev.c
+++ b/Xi/sendexev.c
@@ -135,6 +135,9 @@ ProcXSendExtensionEvent(ClientPtr client)
     if (ret != Success)
         return ret;
 
+    if (stuff->num_events == 0)
+        return ret;
+
     /* The client's event type must be one defined by an extension. */
 
     first = ((xEvent *) &stuff[1]);
diff --git a/Xi/xiallowev.c b/Xi/xiallowev.c
index ebef23344..ca263ef1f 100644
--- a/Xi/xiallowev.c
+++ b/Xi/xiallowev.c
@@ -48,6 +48,7 @@ int
 SProcXIAllowEvents(ClientPtr client)
 {
     REQUEST(xXIAllowEventsReq);
+    REQUEST_AT_LEAST_SIZE(xXIAllowEventsReq);
 
     swaps(&stuff->length);
     swaps(&stuff->deviceid);
@@ -55,6 +56,7 @@ SProcXIAllowEvents(ClientPtr client)
     if (stuff->length > 3) {
         xXI2_2AllowEventsReq *req_xi22 = (xXI2_2AllowEventsReq *) stuff;
 
+        REQUEST_AT_LEAST_SIZE(xXI2_2AllowEventsReq);
         swapl(&req_xi22->touchid);
         swapl(&req_xi22->grab_window);
     }
diff --git a/Xi/xichangecursor.c b/Xi/xichangecursor.c
index 7a1bb7a0d..8e6255b6e 100644
--- a/Xi/xichangecursor.c
+++ b/Xi/xichangecursor.c
@@ -57,11 +57,11 @@ int
 SProcXIChangeCursor(ClientPtr client)
 {
     REQUEST(xXIChangeCursorReq);
+    REQUEST_SIZE_MATCH(xXIChangeCursorReq);
     swaps(&stuff->length);
     swapl(&stuff->win);
     swapl(&stuff->cursor);
     swaps(&stuff->deviceid);
-    REQUEST_SIZE_MATCH(xXIChangeCursorReq);
     return (ProcXIChangeCursor(client));
 }
 
diff --git a/Xi/xichangehierarchy.c b/Xi/xichangehierarchy.c
index 9e36354d1..27324452d 100644
--- a/Xi/xichangehierarchy.c
+++ b/Xi/xichangehierarchy.c
@@ -411,7 +411,7 @@ int
 ProcXIChangeHierarchy(ClientPtr client)
 {
     xXIAnyHierarchyChangeInfo *any;
-    int required_len = sizeof(xXIChangeHierarchyReq);
+    size_t len;			/* length of data remaining in request */
     int rc = Success;
     int flags[MAXDEVICES] = { 0 };
 
@@ -421,21 +421,46 @@ ProcXIChangeHierarchy(ClientPtr client)
     if (!stuff->num_changes)
         return rc;
 
+    if (stuff->length > (INT_MAX >> 2))
+        return BadAlloc;
+    len = (stuff->length << 2) - sizeof(xXIAnyHierarchyChangeInfo);
+
     any = (xXIAnyHierarchyChangeInfo *) &stuff[1];
     while (stuff->num_changes--) {
+        if (len < sizeof(xXIAnyHierarchyChangeInfo)) {
+            rc = BadLength;
+            goto unwind;
+        }
+
         SWAPIF(swaps(&any->type));
         SWAPIF(swaps(&any->length));
 
-        required_len += any->length;
-        if ((stuff->length * 4) < required_len)
+        if ((any->length > (INT_MAX >> 2)) || (len < (any->length << 2)))
             return BadLength;
 
+#define CHANGE_SIZE_MATCH(type) \
+    do { \
+        if ((len < sizeof(type)) || (any->length != (sizeof(type) >> 2))) { \
+            rc = BadLength; \
+            goto unwind; \
+        } \
+    } while(0)
+
         switch (any->type) {
         case XIAddMaster:
         {
             xXIAddMasterInfo *c = (xXIAddMasterInfo *) any;
 
+            /* Variable length, due to appended name string */
+            if (len < sizeof(xXIAddMasterInfo)) {
+                rc = BadLength;
+                goto unwind;
+            }
             SWAPIF(swaps(&c->name_len));
+            if (c->name_len > (len - sizeof(xXIAddMasterInfo))) {
+                rc = BadLength;
+                goto unwind;
+            }
 
             rc = add_master(client, c, flags);
             if (rc != Success)
@@ -446,6 +471,7 @@ ProcXIChangeHierarchy(ClientPtr client)
         {
             xXIRemoveMasterInfo *r = (xXIRemoveMasterInfo *) any;
 
+            CHANGE_SIZE_MATCH(xXIRemoveMasterInfo);
             rc = remove_master(client, r, flags);
             if (rc != Success)
                 goto unwind;
@@ -455,6 +481,7 @@ ProcXIChangeHierarchy(ClientPtr client)
         {
             xXIDetachSlaveInfo *c = (xXIDetachSlaveInfo *) any;
 
+            CHANGE_SIZE_MATCH(xXIDetachSlaveInfo);
             rc = detach_slave(client, c, flags);
             if (rc != Success)
                 goto unwind;
@@ -464,6 +491,7 @@ ProcXIChangeHierarchy(ClientPtr client)
         {
             xXIAttachSlaveInfo *c = (xXIAttachSlaveInfo *) any;
 
+            CHANGE_SIZE_MATCH(xXIAttachSlaveInfo);
             rc = attach_slave(client, c, flags);
             if (rc != Success)
                 goto unwind;
@@ -471,6 +499,7 @@ ProcXIChangeHierarchy(ClientPtr client)
             break;
         }
 
+        len -= any->length * 4;
         any = (xXIAnyHierarchyChangeInfo *) ((char *) any + any->length * 4);
     }
 
diff --git a/Xi/xigetclientpointer.c b/Xi/xigetclientpointer.c
index 3c90d588d..306dd396b 100644
--- a/Xi/xigetclientpointer.c
+++ b/Xi/xigetclientpointer.c
@@ -50,6 +50,7 @@ int
 SProcXIGetClientPointer(ClientPtr client)
 {
     REQUEST(xXIGetClientPointerReq);
+    REQUEST_SIZE_MATCH(xXIGetClientPointerReq);
 
     swaps(&stuff->length);
     swapl(&stuff->win);
diff --git a/Xi/xigrabdev.c b/Xi/xigrabdev.c
index 63d95bc1c..e2a2ae333 100644
--- a/Xi/xigrabdev.c
+++ b/Xi/xigrabdev.c
@@ -47,6 +47,11 @@ int
 SProcXIGrabDevice(ClientPtr client)
 {
     REQUEST(xXIGrabDeviceReq);
+    /*
+     * Check here for at least the length of the struct we swap, then
+     * let ProcXIGrabDevice check the full size after we swap mask_len.
+     */
+    REQUEST_AT_LEAST_SIZE(xXIGrabDeviceReq);
 
     swaps(&stuff->length);
     swaps(&stuff->deviceid);
@@ -71,7 +76,7 @@ ProcXIGrabDevice(ClientPtr client)
     unsigned int pointer_mode;
 
     REQUEST(xXIGrabDeviceReq);
-    REQUEST_AT_LEAST_SIZE(xXIGrabDeviceReq);
+    REQUEST_FIXED_SIZE(xXIGrabDeviceReq, ((size_t) stuff->mask_len) * 4);
 
     ret = dixLookupDevice(&dev, stuff->deviceid, client, DixGrabAccess);
     if (ret != Success)
@@ -131,6 +136,7 @@ int
 SProcXIUngrabDevice(ClientPtr client)
 {
     REQUEST(xXIUngrabDeviceReq);
+    REQUEST_SIZE_MATCH(xXIUngrabDeviceReq);
 
     swaps(&stuff->length);
     swaps(&stuff->deviceid);
@@ -148,6 +154,7 @@ ProcXIUngrabDevice(ClientPtr client)
     TimeStamp time;
 
     REQUEST(xXIUngrabDeviceReq);
+    REQUEST_SIZE_MATCH(xXIUngrabDeviceReq);
 
     ret = dixLookupDevice(&dev, stuff->deviceid, client, DixGetAttrAccess);
     if (ret != Success)
diff --git a/Xi/xipassivegrab.c b/Xi/xipassivegrab.c
index 700622d38..9241ffdea 100644
--- a/Xi/xipassivegrab.c
+++ b/Xi/xipassivegrab.c
@@ -53,6 +53,7 @@ SProcXIPassiveGrabDevice(ClientPtr client)
     uint32_t *mods;
 
     REQUEST(xXIPassiveGrabDeviceReq);
+    REQUEST_AT_LEAST_SIZE(xXIPassiveGrabDeviceReq);
 
     swaps(&stuff->length);
     swaps(&stuff->deviceid);
@@ -63,6 +64,8 @@ SProcXIPassiveGrabDevice(ClientPtr client)
     swaps(&stuff->mask_len);
     swaps(&stuff->num_modifiers);
 
+    REQUEST_FIXED_SIZE(xXIPassiveGrabDeviceReq,
+        ((uint32_t) stuff->mask_len + stuff->num_modifiers) *4);
     mods = (uint32_t *) &stuff[1] + stuff->mask_len;
 
     for (i = 0; i < stuff->num_modifiers; i++, mods++) {
@@ -92,7 +95,8 @@ ProcXIPassiveGrabDevice(ClientPtr client)
     int mask_len;
 
     REQUEST(xXIPassiveGrabDeviceReq);
-    REQUEST_AT_LEAST_SIZE(xXIPassiveGrabDeviceReq);
+    REQUEST_FIXED_SIZE(xXIPassiveGrabDeviceReq,
+        ((uint32_t) stuff->mask_len + stuff->num_modifiers) * 4);
 
     if (stuff->deviceid == XIAllDevices)
         dev = inputInfo.all_devices;
@@ -252,6 +256,7 @@ SProcXIPassiveUngrabDevice(ClientPtr client)
     uint32_t *modifiers;
 
     REQUEST(xXIPassiveUngrabDeviceReq);
+    REQUEST_AT_LEAST_SIZE(xXIPassiveUngrabDeviceReq);
 
     swaps(&stuff->length);
     swapl(&stuff->grab_window);
@@ -259,6 +264,8 @@ SProcXIPassiveUngrabDevice(ClientPtr client)
     swapl(&stuff->detail);
     swaps(&stuff->num_modifiers);
 
+    REQUEST_FIXED_SIZE(xXIPassiveUngrabDeviceReq,
+                       ((uint32_t) stuff->num_modifiers) << 2);
     modifiers = (uint32_t *) &stuff[1];
 
     for (i = 0; i < stuff->num_modifiers; i++, modifiers++)
@@ -277,7 +284,8 @@ ProcXIPassiveUngrabDevice(ClientPtr client)
     int i, rc;
 
     REQUEST(xXIPassiveUngrabDeviceReq);
-    REQUEST_AT_LEAST_SIZE(xXIPassiveUngrabDeviceReq);
+    REQUEST_FIXED_SIZE(xXIPassiveUngrabDeviceReq,
+                       ((uint32_t) stuff->num_modifiers) << 2);
 
     if (stuff->deviceid == XIAllDevices)
         dev = inputInfo.all_devices;
diff --git a/Xi/xiproperty.c b/Xi/xiproperty.c
index 463607d33..8e8e4b061 100644
--- a/Xi/xiproperty.c
+++ b/Xi/xiproperty.c
@@ -1013,10 +1013,9 @@ int
 SProcXListDeviceProperties(ClientPtr client)
 {
     REQUEST(xListDevicePropertiesReq);
+    REQUEST_SIZE_MATCH(xListDevicePropertiesReq);
 
     swaps(&stuff->length);
-
-    REQUEST_SIZE_MATCH(xListDevicePropertiesReq);
     return (ProcXListDeviceProperties(client));
 }
 
@@ -1037,10 +1036,10 @@ int
 SProcXDeleteDeviceProperty(ClientPtr client)
 {
     REQUEST(xDeleteDevicePropertyReq);
+    REQUEST_SIZE_MATCH(xDeleteDevicePropertyReq);
 
     swaps(&stuff->length);
     swapl(&stuff->property);
-    REQUEST_SIZE_MATCH(xDeleteDevicePropertyReq);
     return (ProcXDeleteDeviceProperty(client));
 }
 
@@ -1048,13 +1047,13 @@ int
 SProcXGetDeviceProperty(ClientPtr client)
 {
     REQUEST(xGetDevicePropertyReq);
+    REQUEST_SIZE_MATCH(xGetDevicePropertyReq);
 
     swaps(&stuff->length);
     swapl(&stuff->property);
     swapl(&stuff->type);
     swapl(&stuff->longOffset);
     swapl(&stuff->longLength);
-    REQUEST_SIZE_MATCH(xGetDevicePropertyReq);
     return (ProcXGetDeviceProperty(client));
 }
 
@@ -1253,11 +1252,10 @@ int
 SProcXIListProperties(ClientPtr client)
 {
     REQUEST(xXIListPropertiesReq);
+    REQUEST_SIZE_MATCH(xXIListPropertiesReq);
 
     swaps(&stuff->length);
     swaps(&stuff->deviceid);
-
-    REQUEST_SIZE_MATCH(xXIListPropertiesReq);
     return (ProcXIListProperties(client));
 }
 
@@ -1279,11 +1277,11 @@ int
 SProcXIDeleteProperty(ClientPtr client)
 {
     REQUEST(xXIDeletePropertyReq);
+    REQUEST_SIZE_MATCH(xXIDeletePropertyReq);
 
     swaps(&stuff->length);
     swaps(&stuff->deviceid);
     swapl(&stuff->property);
-    REQUEST_SIZE_MATCH(xXIDeletePropertyReq);
     return (ProcXIDeleteProperty(client));
 }
 
@@ -1291,6 +1289,7 @@ int
 SProcXIGetProperty(ClientPtr client)
 {
     REQUEST(xXIGetPropertyReq);
+    REQUEST_SIZE_MATCH(xXIGetPropertyReq);
 
     swaps(&stuff->length);
     swaps(&stuff->deviceid);
@@ -1298,7 +1297,6 @@ SProcXIGetProperty(ClientPtr client)
     swapl(&stuff->type);
     swapl(&stuff->offset);
     swapl(&stuff->len);
-    REQUEST_SIZE_MATCH(xXIGetPropertyReq);
     return (ProcXIGetProperty(client));
 }
 
diff --git a/Xi/xiquerydevice.c b/Xi/xiquerydevice.c
index 4e544f0f5..67a9a4f3f 100644
--- a/Xi/xiquerydevice.c
+++ b/Xi/xiquerydevice.c
@@ -54,6 +54,7 @@ int
 SProcXIQueryDevice(ClientPtr client)
 {
     REQUEST(xXIQueryDeviceReq);
+    REQUEST_SIZE_MATCH(xXIQueryDeviceReq);
 
     swaps(&stuff->length);
     swaps(&stuff->deviceid);
diff --git a/Xi/xiquerypointer.c b/Xi/xiquerypointer.c
index e9bdd428d..7ec0c851d 100644
--- a/Xi/xiquerypointer.c
+++ b/Xi/xiquerypointer.c
@@ -63,6 +63,8 @@ int
 SProcXIQueryPointer(ClientPtr client)
 {
     REQUEST(xXIQueryPointerReq);
+    REQUEST_SIZE_MATCH(xXIQueryPointerReq);
+
     swaps(&stuff->length);
     swaps(&stuff->deviceid);
     swapl(&stuff->win);
diff --git a/Xi/xiselectev.c b/Xi/xiselectev.c
index 45a996e4c..168579f5b 100644
--- a/Xi/xiselectev.c
+++ b/Xi/xiselectev.c
@@ -114,6 +114,7 @@ int
 SProcXISelectEvents(ClientPtr client)
 {
     int i;
+    int len;
     xXIEventMask *evmask;
 
     REQUEST(xXISelectEventsReq);
@@ -122,10 +123,17 @@ SProcXISelectEvents(ClientPtr client)
     swapl(&stuff->win);
     swaps(&stuff->num_masks);
 
+    len = stuff->length - bytes_to_int32(sizeof(xXISelectEventsReq));
     evmask = (xXIEventMask *) &stuff[1];
     for (i = 0; i < stuff->num_masks; i++) {
+        if (len < bytes_to_int32(sizeof(xXIEventMask)))
+            return BadLength;
+        len -= bytes_to_int32(sizeof(xXIEventMask));
         swaps(&evmask->deviceid);
         swaps(&evmask->mask_len);
+        if (len < evmask->mask_len)
+            return BadLength;
+        len -= evmask->mask_len;
         evmask =
             (xXIEventMask *) (((char *) &evmask[1]) + evmask->mask_len * 4);
     }
diff --git a/Xi/xisetclientpointer.c b/Xi/xisetclientpointer.c
index 38ff51e86..24d4a5379 100644
--- a/Xi/xisetclientpointer.c
+++ b/Xi/xisetclientpointer.c
@@ -51,10 +51,11 @@ int
 SProcXISetClientPointer(ClientPtr client)
 {
     REQUEST(xXISetClientPointerReq);
+    REQUEST_SIZE_MATCH(xXISetClientPointerReq);
+
     swaps(&stuff->length);
     swapl(&stuff->win);
     swaps(&stuff->deviceid);
-    REQUEST_SIZE_MATCH(xXISetClientPointerReq);
     return (ProcXISetClientPointer(client));
 }
 
diff --git a/Xi/xisetdevfocus.c b/Xi/xisetdevfocus.c
index 372ec248a..96a9a16e4 100644
--- a/Xi/xisetdevfocus.c
+++ b/Xi/xisetdevfocus.c
@@ -44,6 +44,8 @@ int
 SProcXISetFocus(ClientPtr client)
 {
     REQUEST(xXISetFocusReq);
+    REQUEST_AT_LEAST_SIZE(xXISetFocusReq);
+
     swaps(&stuff->length);
     swaps(&stuff->deviceid);
     swapl(&stuff->focus);
@@ -56,6 +58,8 @@ int
 SProcXIGetFocus(ClientPtr client)
 {
     REQUEST(xXIGetFocusReq);
+    REQUEST_AT_LEAST_SIZE(xXIGetFocusReq);
+
     swaps(&stuff->length);
     swaps(&stuff->deviceid);
 
diff --git a/Xi/xiwarppointer.c b/Xi/xiwarppointer.c
index 3f051f759..780758a9e 100644
--- a/Xi/xiwarppointer.c
+++ b/Xi/xiwarppointer.c
@@ -56,6 +56,8 @@ int
 SProcXIWarpPointer(ClientPtr client)
 {
     REQUEST(xXIWarpPointerReq);
+    REQUEST_SIZE_MATCH(xXIWarpPointerReq);
+
     swaps(&stuff->length);
     swapl(&stuff->src_win);
     swapl(&stuff->dst_win);
diff --git a/include/dix.h b/include/dix.h
index 9bbbba9c6..41892863e 100644
--- a/include/dix.h
+++ b/include/dix.h
@@ -74,6 +74,10 @@ SOFTWARE.
     if ((sizeof(req) >> 2) > client->req_len )\
          return(BadLength)
 
+#define REQUEST_AT_LEAST_EXTRA_SIZE(req, extra)  \
+    if (((sizeof(req) + ((uint64_t) extra)) >> 2) > client->req_len ) \
+         return(BadLength)
+
 #define REQUEST_FIXED_SIZE(req, n)\
     if (((sizeof(req) >> 2) > client->req_len) || \
         ((n >> 2) >= client->req_len) || \