x86/mem_event: validate the response vcpu_id before acting on it

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Tim Deegan <tim@xen.org>
Reviewed-by: Andres Lagar-Cavilla <andres@lagarcavilla.org>
Tested-by: Razvan Cojocaru <rcojocaru@bitdefender.com>

diff --git a/xen/arch/x86/mm/mem_sharing.c b/xen/arch/x86/mm/mem_sharing.c
index 7293f319cba25cd2ea65e8de150b20c0a303748f..ec99266280b5881fcf4b600146a386c81e301950 100644 (file)
--- a/xen/arch/x86/mm/mem_sharing.c
+++ b/xen/arch/x86/mm/mem_sharing.c
@@ -596,11 +596,20 @@ int mem_sharing_sharing_resume(struct domain *d)
     /* Get all requests off the ring */
     while ( mem_event_get_response(d, &d->mem_event->share, &rsp) )
     {
+        struct vcpu *v;
+
         if ( rsp.flags & MEM_EVENT_FLAG_DUMMY )
             continue;
+
+        /* Validate the vcpu_id in the response. */
+        if ( (rsp.vcpu_id >= d->max_vcpus) || !d->vcpu[rsp.vcpu_id] )
+            continue;
+
+        v = d->vcpu[rsp.vcpu_id];
+
         /* Unpause domain/vcpu */
         if ( rsp.flags & MEM_EVENT_FLAG_VCPU_PAUSED )
-            vcpu_unpause(d->vcpu[rsp.vcpu_id]);
+            vcpu_unpause(v);
     }
 
     return 0;

diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 642ec28889d6913e221f13775916c0f6528b6911..f213a392c137a6d516c52be1d9007af82094f1a4 100644 (file)
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -1290,8 +1290,17 @@ void p2m_mem_paging_resume(struct domain *d)
     /* Pull all responses off the ring */
     while( mem_event_get_response(d, &d->mem_event->paging, &rsp) )
     {
+        struct vcpu *v;
+
         if ( rsp.flags & MEM_EVENT_FLAG_DUMMY )
             continue;
+
+        /* Validate the vcpu_id in the response. */
+        if ( (rsp.vcpu_id >= d->max_vcpus) || !d->vcpu[rsp.vcpu_id] )
+            continue;
+
+        v = d->vcpu[rsp.vcpu_id];
+
         /* Fix p2m entry if the page was not dropped */
         if ( !(rsp.flags & MEM_EVENT_FLAG_DROP_PAGE) )
         {
@@ -1310,7 +1319,7 @@ void p2m_mem_paging_resume(struct domain *d)
         }
         /* Unpause domain */
         if ( rsp.flags & MEM_EVENT_FLAG_VCPU_PAUSED )
-            vcpu_unpause(d->vcpu[rsp.vcpu_id]);
+            vcpu_unpause(v);
     }
 }
 
@@ -1418,11 +1427,20 @@ void p2m_mem_access_resume(struct domain *d)
     /* Pull all responses off the ring */
     while( mem_event_get_response(d, &d->mem_event->access, &rsp) )
     {
+        struct vcpu *v;
+
         if ( rsp.flags & MEM_EVENT_FLAG_DUMMY )
             continue;
+
+        /* Validate the vcpu_id in the response. */
+        if ( (rsp.vcpu_id >= d->max_vcpus) || !d->vcpu[rsp.vcpu_id] )
+            continue;
+
+        v = d->vcpu[rsp.vcpu_id];
+
         /* Unpause domain */
         if ( rsp.flags & MEM_EVENT_FLAG_VCPU_PAUSED )
-            vcpu_unpause(d->vcpu[rsp.vcpu_id]);
+            vcpu_unpause(v);
     }
 }