From patchwork Thu Oct 17 19:39:22 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Al Viro X-Patchwork-Id: 11197039 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 03EA8139A for ; Thu, 17 Oct 2019 19:40:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E192321A49 for ; Thu, 17 Oct 2019 19:40:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2436975AbfJQTkN (ORCPT ); Thu, 17 Oct 2019 15:40:13 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:45062 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2437743AbfJQTjp (ORCPT ); Thu, 17 Oct 2019 15:39:45 -0400 Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1iLBcd-0006fP-Rw; Thu, 17 Oct 2019 19:39:43 +0000 From: Al Viro To: linux-scsi@vger.kernel.org Cc: Linus Torvalds , linux-kernel@vger.kernel.org, Al Viro Subject: [RFC PATCH 5/8] sg_new_write(): don't bother with access_ok Date: Thu, 17 Oct 2019 20:39:22 +0100 Message-Id: <20191017193925.25539-5-viro@ZenIV.linux.org.uk> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191017193925.25539-1-viro@ZenIV.linux.org.uk> References: <20191017193659.GA18702@ZenIV.linux.org.uk> <20191017193925.25539-1-viro@ZenIV.linux.org.uk> MIME-Version: 1.0 Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org From: Al Viro ... just use copy_from_user(). We copy only SZ_SG_IO_HDR bytes, so that would, strictly speaking, loosen the check. However, for call chains via ->write() the caller has actually checked the entire range and SG_IO passes exactly SZ_SG_IO_HDR for count. So no visible behaviour changes happen if we check only what we really need for copyin. Signed-off-by: Al Viro --- drivers/scsi/sg.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c index 2d30e89075e9..3702f66493f7 100644 --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -717,8 +717,6 @@ sg_new_write(Sg_fd *sfp, struct file *file, const char __user *buf, if (count < SZ_SG_IO_HDR) return -EINVAL; - if (!access_ok(buf, count)) - return -EFAULT; /* protects following copy_from_user()s + get_user()s */ sfp->cmd_q = 1; /* when sg_io_hdr seen, set command queuing on */ if (!(srp = sg_add_request(sfp))) { @@ -728,7 +726,7 @@ sg_new_write(Sg_fd *sfp, struct file *file, const char __user *buf, } srp->sg_io_owned = sg_io_owned; hp = &srp->header; - if (__copy_from_user(hp, buf, SZ_SG_IO_HDR)) { + if (copy_from_user(hp, buf, SZ_SG_IO_HDR)) { sg_remove_request(sfp, srp); return -EFAULT; }