From 55281a2c53b884d0c2bce31aee592faf20a28eed Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Thu, 13 Dec 2018 12:02:52 +0000 Subject: [PATCH] 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: Peter Maydell Message-Id: <20181213120252.21697-1-peter.maydell@linaro.org> Reviewed-by: Farhan Ali Reviewed-by: Thomas Huth Signed-off-by: Cornelia Huck --- hw/s390x/css.c | 32 ++++++++++++++++++++++++++------ 1 file changed, 26 insertions(+), 6 deletions(-) diff --git a/hw/s390x/css.c b/hw/s390x/css.c index 04ec5cc970..f92b046cd3 100644 --- a/hw/s390x/css.c +++ b/hw/s390x/css.c @@ -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]; -- 2.30.2