[Xen-changelog] Saner error handling in iret hypercall (x86/64).

[Xen patchbot -3.0-testing <patchbot-3.0-testing@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kaf24@xxxxxxxxxxxxxxxxxxxx
# Node ID 459e6131c07dc69eb77e05f65e655f949c4e1a47
# Parent  9d4528f9b99011350a8308fce988db9f2f2d13bc
Saner error handling in iret hypercall (x86/64).

Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>

diff -r 9d4528f9b990 -r 459e6131c07d xen/arch/x86/x86_64/traps.c
--- a/xen/arch/x86/x86_64/traps.c       Thu Apr  6 13:59:23 2006
+++ b/xen/arch/x86/x86_64/traps.c       Thu Apr  6 14:57:51 2006
@@ -184,13 +184,19 @@
 
     if ( unlikely(copy_from_user(&iret_saved, (void *)regs->rsp,
                                  sizeof(iret_saved))) )
+    {
+        DPRINTK("Fault while reading IRET context from guest stack\n");
         domain_crash_synchronous();
+    }
 
     /* Returning to user mode? */
     if ( (iret_saved.cs & 3) == 3 )
     {
         if ( unlikely(pagetable_get_paddr(v->arch.guest_table_user) == 0) )
-            return -EFAULT;
+        {
+            DPRINTK("Guest switching to user mode with no user page tables\n");
+            domain_crash_synchronous();
+        }
         toggle_guest_mode(v);
     }
 

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