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    Subject[PATCH 5.14 020/151] xen/privcmd: fix error handling in mmap-resource processing
    Date
    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;
    }

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