Commit 55281a2c authored by Peter Maydell's avatar Peter Maydell Committed by Cornelia Huck
Browse files

hw/s390/ccw.c: Don't take address of packed members 



Taking the address of a field in a packed struct is a bad idea, because
it might not be actually aligned enough for that pointer type (and
thus cause a crash on dereference on some host architectures). Newer
versions of clang warn about this.

Avoid the problem by using local copies of the PMCW and SCSW
struct fields in copy_schib_from_guest() and copy_schib_to_guest().

Signed-off-by: default avatarPeter Maydell <peter.maydell@linaro.org>
Message-Id: <20181213120252.21697-1-peter.maydell@linaro.org>
Reviewed-by: default avatarFarhan Ali <alifm@linux.ibm.com>
Reviewed-by: default avatarThomas Huth <thuth@redhat.com>
Signed-off-by: default avatarCornelia Huck <cohuck@redhat.com>
parent b72566a4

hw/s390x/css.c

+26 −6
Original line number Diff line number Diff line
@@ -1290,9 +1290,19 @@ void copy_scsw_to_guest(SCSW *dest, const SCSW *src) 
static void copy_schib_to_guest(SCHIB *dest, const SCHIB *src)

{

    int i;



    copy_pmcw_to_guest(&dest->pmcw, &src->pmcw);

    copy_scsw_to_guest(&dest->scsw, &src->scsw);

    /*

     * We copy the PMCW and SCSW in and out of local variables to

     * avoid taking the address of members of a packed struct.

     */

    PMCW src_pmcw, dest_pmcw;

    SCSW src_scsw, dest_scsw;



    src_pmcw = src->pmcw;

    copy_pmcw_to_guest(&dest_pmcw, &src_pmcw);

    dest->pmcw = dest_pmcw;

    src_scsw = src->scsw;

    copy_scsw_to_guest(&dest_scsw, &src_scsw);

    dest->scsw = dest_scsw;

    dest->mba = cpu_to_be64(src->mba);

    for (i = 0; i < ARRAY_SIZE(dest->mda); i++) {

        dest->mda[i] = src->mda[i];
@@ -1339,9 +1349,19 @@ static void copy_scsw_from_guest(SCSW *dest, const SCSW *src) 
static void copy_schib_from_guest(SCHIB *dest, const SCHIB *src)

{

    int i;



    copy_pmcw_from_guest(&dest->pmcw, &src->pmcw);

    copy_scsw_from_guest(&dest->scsw, &src->scsw);

    /*

     * We copy the PMCW and SCSW in and out of local variables to

     * avoid taking the address of members of a packed struct.

     */

    PMCW src_pmcw, dest_pmcw;

    SCSW src_scsw, dest_scsw;



    src_pmcw = src->pmcw;

    copy_pmcw_from_guest(&dest_pmcw, &src_pmcw);

    dest->pmcw = dest_pmcw;

    src_scsw = src->scsw;

    copy_scsw_from_guest(&dest_scsw, &src_scsw);

    dest->scsw = dest_scsw;

    dest->mba = be64_to_cpu(src->mba);

    for (i = 0; i < ARRAY_SIZE(dest->mda); i++) {

        dest->mda[i] = src->mda[i];