common: map_vcpu_info() cosmetics

Use ENXIO instead of EINVAL to cover the two cases of the address not
satisfying the requirements. This will make an issue here better stand
out at the call site.

Also add a missing compat-mode related size check: If the sizes
differed, other code in the function would need changing. Accompany this
by a change to the initial sizeof() expression, tying it to the type of
the variable we're actually after (matching e.g. the alignof() added by
XSA-327).

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Julien Grall <jgrall@amazon.com>

diff --git a/xen/common/domain.c b/xen/common/domain.c
index d85984638ab6a51b28494e3f78356a7a49d98792..cdda0d1f29aeed19a1ddacb7416d7938f295c1af 100644 (file)
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -1427,17 +1427,18 @@ int map_vcpu_info(struct vcpu *v, unsigned long gfn, unsigned offset)
     struct page_info *page;
     unsigned int align;
 
-    if ( offset > (PAGE_SIZE - sizeof(vcpu_info_t)) )
-        return -EINVAL;
+    if ( offset > (PAGE_SIZE - sizeof(*new_info)) )
+        return -ENXIO;
 
 #ifdef CONFIG_COMPAT
+    BUILD_BUG_ON(sizeof(*new_info) != sizeof(new_info->compat));
     if ( has_32bit_shinfo(d) )
         align = alignof(new_info->compat);
     else
 #endif
         align = alignof(*new_info);
     if ( offset & (align - 1) )
-        return -EINVAL;
+        return -ENXIO;
 
     if ( !mfn_eq(v->vcpu_info_mfn, INVALID_MFN) )
         return -EINVAL;