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

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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: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20181213120252.21697-1-peter.maydell@linaro.org>
Reviewed-by: Farhan Ali <alifm@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
This commit is contained in:
Peter Maydell 2018-12-13 12:02:52 +00:00 committed by Cornelia Huck
parent b72566a4ff
commit 55281a2c53
1 changed files with 24 additions and 4 deletions
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28
hw/s390x/css.c
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@ -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;
/*
* 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;
copy_pmcw_to_guest(&dest->pmcw, &src->pmcw);
copy_scsw_to_guest(&dest->scsw, &src->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;
/*
* 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;
copy_pmcw_from_guest(&dest->pmcw, &src->pmcw);
copy_scsw_from_guest(&dest->scsw, &src->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];