[PATCH v2 1/2] x86/hvm/dmop: fix EFAULT condition

[Wei Liu <wei.liu2@citrix.com>]

The copy macro returns false when the copy fails.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
---
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Paul Durrant <paul.durrant@citrix.com>

Backport to 4.9
---
 xen/arch/x86/hvm/dm.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/hvm/dm.c b/xen/arch/x86/hvm/dm.c
index 87ef4b6ca9..9cf53b551c 100644
--- a/xen/arch/x86/hvm/dm.c
+++ b/xen/arch/x86/hvm/dm.c
@@ -178,11 +178,9 @@ static int modified_memory(struct domain *d,
         struct xen_dm_op_modified_memory_extent extent;
         unsigned int batch_nr;
         xen_pfn_t pfn, end_pfn;
-        int rc;
 
-        rc = COPY_FROM_GUEST_BUF_OFFSET(extent,
-            bufs, EXTENTS_BUFFER, (*rem_extents - 1) * sizeof(extent));
-        if ( rc )
+        if ( !COPY_FROM_GUEST_BUF_OFFSET(extent, bufs, EXTENTS_BUFFER,
+                                         (*rem_extents - 1) * sizeof(extent)) )
             return -EFAULT;
 
         if ( extent.pad )
-- 
2.11.0


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