From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50363) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gJhtJ-0006wm-13 for qemu-devel@nongnu.org; Mon, 05 Nov 2018 11:38:21 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gJhtH-0003V2-9z for qemu-devel@nongnu.org; Mon, 05 Nov 2018 11:38:16 -0500 From: Kevin Wolf Date: Mon, 5 Nov 2018 17:37:13 +0100 Message-Id: <20181105163744.25139-6-kwolf@redhat.com> In-Reply-To: <20181105163744.25139-1-kwolf@redhat.com> References: <20181105163744.25139-1-kwolf@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Subject: [Qemu-devel] [PULL 05/36] block/qcow: Don't take address of fields in packed structs List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-block@nongnu.org Cc: kwolf@redhat.com, peter.maydell@linaro.org, qemu-devel@nongnu.org From: Peter Maydell 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 bug by not using the "modify in place" byte swapping functions. There are a few places where the in-place swap function is used on something other than a packed struct field; we convert those anyway, for consistency. This patch was produced with the following spatch script: @@ expression E; @@ -be16_to_cpus(&E); +E =3D be16_to_cpu(E); @@ expression E; @@ -be32_to_cpus(&E); +E =3D be32_to_cpu(E); @@ expression E; @@ -be64_to_cpus(&E); +E =3D be64_to_cpu(E); @@ expression E; @@ -cpu_to_be16s(&E); +E =3D cpu_to_be16(E); @@ expression E; @@ -cpu_to_be32s(&E); +E =3D cpu_to_be32(E); @@ expression E; @@ -cpu_to_be64s(&E); +E =3D cpu_to_be64(E); Signed-off-by: Peter Maydell Reviewed-by: Richard Henderson Tested-by: John Snow Reviewed-by: John Snow Signed-off-by: Kevin Wolf --- block/qcow.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/block/qcow.c b/block/qcow.c index 385d935258..4518cb4c35 100644 --- a/block/qcow.c +++ b/block/qcow.c @@ -140,14 +140,14 @@ static int qcow_open(BlockDriverState *bs, QDict *o= ptions, int flags, if (ret < 0) { goto fail; } - be32_to_cpus(&header.magic); - be32_to_cpus(&header.version); - be64_to_cpus(&header.backing_file_offset); - be32_to_cpus(&header.backing_file_size); - be32_to_cpus(&header.mtime); - be64_to_cpus(&header.size); - be32_to_cpus(&header.crypt_method); - be64_to_cpus(&header.l1_table_offset); + header.magic =3D be32_to_cpu(header.magic); + header.version =3D be32_to_cpu(header.version); + header.backing_file_offset =3D be64_to_cpu(header.backing_file_offse= t); + header.backing_file_size =3D be32_to_cpu(header.backing_file_size); + header.mtime =3D be32_to_cpu(header.mtime); + header.size =3D be64_to_cpu(header.size); + header.crypt_method =3D be32_to_cpu(header.crypt_method); + header.l1_table_offset =3D be64_to_cpu(header.l1_table_offset); =20 if (header.magic !=3D QCOW_MAGIC) { error_setg(errp, "Image not in qcow format"); @@ -270,7 +270,7 @@ static int qcow_open(BlockDriverState *bs, QDict *opt= ions, int flags, } =20 for(i =3D 0;i < s->l1_size; i++) { - be64_to_cpus(&s->l1_table[i]); + s->l1_table[i] =3D be64_to_cpu(s->l1_table[i]); } =20 /* alloc L2 cache (max. 64k * 16 * 8 =3D 8 MB) */ --=20 2.19.1