From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-by2nam01on0078.outbound.protection.outlook.com ([104.47.34.78]:33543 "EHLO NAM01-BY2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750746AbcINIqd (ORCPT ); Wed, 14 Sep 2016 04:46:33 -0400 Subject: [PATCH 3/3] block: Improve bio_set_op_attrs() robustness To: Jens Axboe References: <35e3cdd6-8983-6c84-cb4c-9a7be15aea55@sandisk.com> CC: Mike Christie , Chris Mason , Josef Bacik , Mike Snitzer , Christoph Hellwig , Hannes Reinecke , Damien Le Moal , "linux-block@vger.kernel.org" , "linux-btrfs@vger.kernel.org" , device-mapper development From: Bart Van Assche Message-ID: <2a6c6cbd-ccc6-ee89-99ca-c0267cf17ec0@sandisk.com> Date: Wed, 14 Sep 2016 10:46:22 +0200 MIME-Version: 1.0 In-Reply-To: <35e3cdd6-8983-6c84-cb4c-9a7be15aea55@sandisk.com> Content-Type: text/plain; charset="utf-8" Sender: linux-block-owner@vger.kernel.org List-Id: linux-block@vger.kernel.org Since REQ_OP_BITS == 3 and __REQ_NR_BITS == 30 it is not that hard to pass an op_flags argument to bio_set_op_attrs() that is larger than the number of bits reserved for the op_flags argument. Complain if this happens. Additionally, ensure that negative arguments trigger a complaint (1 << ... is signed while 1U << ... is unsigned; adding 0U to an integer expression causes it to be promoted to an unsigned type). Signed-off-by: Bart Van Assche Cc: Mike Christie Cc: Christoph Hellwig Cc: Hannes Reinecke Cc: Damien Le Moal --- include/linux/blk_types.h | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h index 311fa2f..53ee1a2 100644 --- a/include/linux/blk_types.h +++ b/include/linux/blk_types.h @@ -93,11 +93,18 @@ struct bio { #define bio_flags(bio) ((bio)->bi_opf & ((1 << BIO_OP_SHIFT) - 1)) #define bio_op(bio) ((bio)->bi_opf >> BIO_OP_SHIFT) -#define bio_set_op_attrs(bio, op, op_flags) do { \ - WARN_ON(op >= (1 << REQ_OP_BITS)); \ - (bio)->bi_opf = bio_flags(bio); \ - (bio)->bi_opf |= ((unsigned int) (op) << BIO_OP_SHIFT); \ - (bio)->bi_opf |= op_flags; \ +#define bio_set_op_attrs(bio, op, op_flags) do { \ + if (__builtin_constant_p(op)) \ + BUILD_BUG_ON((op) + 0U >= (1U << REQ_OP_BITS)); \ + else \ + WARN_ON_ONCE((op) + 0U >= (1U << REQ_OP_BITS)); \ + if (__builtin_constant_p(op_flags)) \ + BUILD_BUG_ON((op_flags) + 0U >= (1U << BIO_OP_SHIFT)); \ + else \ + WARN_ON_ONCE((op_flags) + 0U >= (1U << BIO_OP_SHIFT)); \ + (bio)->bi_opf = bio_flags(bio); \ + (bio)->bi_opf |= (((op) + 0U) << BIO_OP_SHIFT); \ + (bio)->bi_opf |= (op_flags); \ } while (0) #define BIO_RESET_BYTES offsetof(struct bio, bi_max_vecs) -- 2.10.0