File 67921698-x86-HVM-MMIO-emul-cache-bounds-check.patch of Package xen.37689

# Commit e5339bb689dfa79a914c6c96e1d82d61e1ae3161
# Date 2025-01-23 11:14:48 +0100
# Author Jan Beulich <jbeulich@suse.com>
# Committer Jan Beulich <jbeulich@suse.com>
x86/HVM: correct MMIO emulation cache bounds check

To avoid overrunning the internal buffer we need to take the offset into
the buffer into account.

Fixes: d95da91fb497 ("x86/HVM: grow MMIO cache data size to 64 bytes")
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>

--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -937,7 +937,7 @@ static int hvmemul_phys_mmio_access(
     }
 
     /* Accesses must not overflow the cache's buffer. */
-    if ( size > sizeof(cache->buffer) )
+    if ( offset + size > sizeof(cache->buffer) )
     {
         ASSERT_UNREACHABLE();
         return X86EMUL_UNHANDLEABLE;