xen/privcmd: fix error handling in mmap-resource processing

commit e11423d6721dd63b23fb41ade5e8d0b448b17780 upstream.

xen_pfn_t is the same size as int only on 32-bit builds (and not even
on Arm32). Hence pfns[] can't be used directly to read individual error
values returned from xen_remap_domain_mfn_array(); every other error
indicator would be skipped/ignored on 64-bit.

Fixes: 3ad0876554ca ("xen/privcmd: add IOCTL_PRIVCMD_MMAP_RESOURCE")
Cc: stable@vger.kernel.org
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/aa6d6a67-6889-338a-a910-51e889f792d5@suse.com
Signed-off-by: Juergen Gross <jgross@suse.com>

diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
index a8486432be05abc70730a6e142eab9921eae7bca..74ff28fda64dc37ac9ca4907583962d424dd3bea 100644 (file)
--- a/drivers/xen/privcmd.c
+++ b/drivers/xen/privcmd.c
@@ -835,11 +835,12 @@ static long privcmd_ioctl_mmap_resource(struct file *file,
                unsigned int domid =
                        (xdata.flags & XENMEM_rsrc_acq_caller_owned) ?
                        DOMID_SELF : kdata.dom;
-               int num;
+               int num, *errs = (int *)pfns;
 
+               BUILD_BUG_ON(sizeof(*errs) > sizeof(*pfns));
                num = xen_remap_domain_mfn_array(vma,
                                                 kdata.addr & PAGE_MASK,
-                                                pfns, kdata.num, (int *)pfns,
+                                                pfns, kdata.num, errs,
                                                 vma->vm_page_prot,
                                                 domid,
                                                 vma->vm_private_data);
@@ -849,7 +850,7 @@ static long privcmd_ioctl_mmap_resource(struct file *file,
                        unsigned int i;
 
                        for (i = 0; i < num; i++) {
-                               rc = pfns[i];
+                               rc = errs[i];
                                if (rc < 0)
                                        break;
                        }