[xen master] gnttab: bail from GFN-storing loops early in case of error

[patchbot@xxxxxxx]

commit 5488cc3a4d7caa75259cdeb5f5b9da227fc12360
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Fri Dec 2 10:25:59 2022 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Dec 2 10:25:59 2022 +0100

    gnttab: bail from GFN-storing loops early in case of error
    
    The contents of the output arrays are undefined anyway when the
    operation itself gets marked as failed. There's no value in trying to
    continue after a guest memory access failure.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/common/compat/grant_table.c | 3 +++
 xen/common/grant_table.c        | 6 ++++++
 2 files changed, 9 insertions(+)

diff --git a/xen/common/compat/grant_table.c b/xen/common/compat/grant_table.c
index 4f6d0b05fb..744f9b6e3d 100644
--- a/xen/common/compat/grant_table.c
+++ b/xen/common/compat/grant_table.c
@@ -179,7 +179,10 @@ int compat_grant_table_op(
                             unsigned int frame = (_s_)->frame_list.p[i]; \
                             if ( __copy_to_compat_offset((_d_)->frame_list, \
                                                          i, &frame, 1) ) \
+                            { \
                                 (_s_)->status = GNTST_bad_virt_addr; \
+                                break; \
+                            } \
                         } \
                     } \
                 } while (0)
diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c
index 6326bae5aa..fa28c3cb7b 100644
--- a/xen/common/grant_table.c
+++ b/xen/common/grant_table.c
@@ -2101,7 +2101,10 @@ gnttab_setup_table(
         BUG_ON(SHARED_M2P(gmfn));
 
         if ( __copy_to_guest_offset(op.frame_list, i, &gmfn, 1) )
+        {
             op.status = GNTST_bad_virt_addr;
+            break;
+        }
     }
 
  unlock:
@@ -3311,7 +3314,10 @@ 
gnttab_get_status_frames(XEN_GUEST_HANDLE_PARAM(gnttab_get_status_frames_t) uop,
     {
         gmfn = gfn_x(gnttab_status_gfn(d, gt, i));
         if ( __copy_to_guest_offset(op.frame_list, i, &gmfn, 1) )
+        {
             op.status = GNTST_bad_virt_addr;
+            break;
+        }
     }
 
  unlock:
--
generated by git-patchbot for /home/xen/git/xen.git#master