From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54634) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gWJiK-0007KN-4I for qemu-devel@nongnu.org; Mon, 10 Dec 2018 06:27:05 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gWJiJ-00064c-44 for qemu-devel@nongnu.org; Mon, 10 Dec 2018 06:27:04 -0500 From: Peter Maydell Date: Mon, 10 Dec 2018 11:26:48 +0000 Message-Id: <20181210112649.11581-3-peter.maydell@linaro.org> In-Reply-To: <20181210112649.11581-1-peter.maydell@linaro.org> References: <20181210112649.11581-1-peter.maydell@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Subject: [Qemu-devel] [PATCH 2/3] block/vdi: Don't take address of fields in packed structs List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: patches@linaro.org, qemu-block@nongnu.org, Fam Zheng , Igor Mammedov , "Michael S. Tsirkin" , Ben Warren , Max Reitz , Kevin Wolf , Stefan Weil 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. Instead of passing UUID related functions the address of a possibly unaligned QemuUUID struct, use local variables and then copy to/from the struct field as appropriate. Signed-off-by: Peter Maydell --- block/vdi.c | 38 +++++++++++++++++++++++++------------- 1 file changed, 25 insertions(+), 13 deletions(-) diff --git a/block/vdi.c b/block/vdi.c index 2380daa583e..4cc726047c3 100644 --- a/block/vdi.c +++ b/block/vdi.c @@ -235,7 +235,8 @@ static void vdi_header_to_le(VdiHeader *header) static void vdi_header_print(VdiHeader *header) { - char uuid[37]; + char uuidstr[37]; + QemuUUID uuid; logout("text %s", header->text); logout("signature 0x%08x\n", header->signature); logout("header size 0x%04x\n", header->header_size); @@ -254,14 +255,18 @@ static void vdi_header_print(VdiHeader *header) logout("block extra 0x%04x\n", header->block_extra); logout("blocks tot. 0x%04x\n", header->blocks_in_image); logout("blocks all. 0x%04x\n", header->blocks_allocated); - qemu_uuid_unparse(&header->uuid_image, uuid); - logout("uuid image %s\n", uuid); - qemu_uuid_unparse(&header->uuid_last_snap, uuid); - logout("uuid snap %s\n", uuid); - qemu_uuid_unparse(&header->uuid_link, uuid); - logout("uuid link %s\n", uuid); - qemu_uuid_unparse(&header->uuid_parent, uuid); - logout("uuid parent %s\n", uuid); + uuid = header->uuid_image; + qemu_uuid_unparse(&uuid, uuidstr); + logout("uuid image %s\n", uuidstr); + uuid = header->uuid_last_snap; + qemu_uuid_unparse(&uuid, uuidstr); + logout("uuid snap %s\n", uuidstr); + uuid = header->uuid_link; + qemu_uuid_unparse(&uuid, uuidstr); + logout("uuid link %s\n", uuidstr); + uuid = header->uuid_parent; + qemu_uuid_unparse(&uuid, uuidstr); + logout("uuid parent %s\n", uuidstr); } static int coroutine_fn vdi_co_check(BlockDriverState *bs, BdrvCheckResult *res, @@ -368,6 +373,7 @@ static int vdi_open(BlockDriverState *bs, QDict *options, int flags, size_t bmap_size; int ret; Error *local_err = NULL; + QemuUUID uuid_link, uuid_parent; bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file, false, errp); @@ -395,6 +401,9 @@ static int vdi_open(BlockDriverState *bs, QDict *options, int flags, goto fail; } + uuid_link = header.uuid_link; + uuid_parent = header.uuid_parent; + if (header.disk_size % SECTOR_SIZE != 0) { /* 'VBoxManage convertfromraw' can create images with odd disk sizes. We accept them but round the disk size to the next multiple of @@ -444,11 +453,11 @@ static int vdi_open(BlockDriverState *bs, QDict *options, int flags, (uint64_t)header.blocks_in_image * header.block_size); ret = -ENOTSUP; goto fail; - } else if (!qemu_uuid_is_null(&header.uuid_link)) { + } else if (!qemu_uuid_is_null(&uuid_link)) { error_setg(errp, "unsupported VDI image (non-NULL link UUID)"); ret = -ENOTSUP; goto fail; - } else if (!qemu_uuid_is_null(&header.uuid_parent)) { + } else if (!qemu_uuid_is_null(&uuid_parent)) { error_setg(errp, "unsupported VDI image (non-NULL parent UUID)"); ret = -ENOTSUP; goto fail; @@ -733,6 +742,7 @@ static int coroutine_fn vdi_co_do_create(BlockdevCreateOptions *create_options, BlockDriverState *bs_file = NULL; BlockBackend *blk = NULL; uint32_t *bmap = NULL; + QemuUUID uuid; assert(create_options->driver == BLOCKDEV_DRIVER_VDI); vdi_opts = &create_options->u.vdi; @@ -819,8 +829,10 @@ static int coroutine_fn vdi_co_do_create(BlockdevCreateOptions *create_options, if (image_type == VDI_TYPE_STATIC) { header.blocks_allocated = blocks; } - qemu_uuid_generate(&header.uuid_image); - qemu_uuid_generate(&header.uuid_last_snap); + qemu_uuid_generate(&uuid); + header.uuid_image = uuid; + qemu_uuid_generate(&uuid); + header.uuid_last_snap = uuid; /* There is no need to set header.uuid_link or header.uuid_parent here. */ if (VDI_DEBUG) { vdi_header_print(&header); -- 2.19.2