[PATCH 5.10 07/83] xen/privcmd: fix error handling in mmap-resource processing

Greg Kroah-Hartman
2021-10-11T13:54:59Z

From: Jan Beulich <jbeulich@suse.com>

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>
---
drivers/xen/privcmd.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

--- a/drivers/xen/privcmd.c
+++ b/drivers/xen/privcmd.c
@@ -803,11 +803,12 @@ static long privcmd_ioctl_mmap_resource(
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);
@@ -817,7 +818,7 @@ static long privcmd_ioctl_mmap_resource(
unsigned int i;

for (i = 0; i < num; i++) {
- rc = pfns[i];
+ rc = errs[i];
if (rc < 0)
break;
}