From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3371FC54FCC for ; Tue, 21 Apr 2020 18:52:11 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A9D6A2068F for ; Tue, 21 Apr 2020 18:52:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A9D6A2068F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zeniv.linux.org.uk Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 496CNR1RGXzDqxc for ; Wed, 22 Apr 2020 04:52:07 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=ftp.linux.org.uk (client-ip=2002:c35c:fd02::1; helo=zeniv.linux.org.uk; envelope-from=viro@ftp.linux.org.uk; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=zeniv.linux.org.uk Received: from ZenIV.linux.org.uk (zeniv.linux.org.uk [IPv6:2002:c35c:fd02::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 496CL25TM2zDqvW for ; Wed, 22 Apr 2020 04:50:02 +1000 (AEST) Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1jQxxl-007lIL-Bu; Tue, 21 Apr 2020 18:49:41 +0000 Date: Tue, 21 Apr 2020 19:49:41 +0100 From: Al Viro To: Christoph Hellwig Subject: Re: [PATCH 1/7] powerpc/spufs: simplify spufs core dumping Message-ID: <20200421184941.GD23230@ZenIV.linux.org.uk> References: <20200421154204.252921-1-hch@lst.de> <20200421154204.252921-2-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200421154204.252921-2-hch@lst.de> X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Arnd Bergmann , linux-kernel@vger.kernel.org, Jeremy Kerr , linux-fsdevel@vger.kernel.org, Andrew Morton , linuxppc-dev@lists.ozlabs.org, "Eric W . Biederman" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Tue, Apr 21, 2020 at 05:41:58PM +0200, Christoph Hellwig wrote: > static ssize_t spufs_proxydma_info_read(struct file *file, char __user *buf, > size_t len, loff_t *pos) > { > struct spu_context *ctx = file->private_data; > + struct spu_proxydma_info info; > int ret; > > + if (len < sizeof(info)) > + return -EINVAL; > + if (!access_ok(buf, len)) > + return -EFAULT; > + > ret = spu_acquire_saved(ctx); > if (ret) > return ret; > spin_lock(&ctx->csa.register_lock); > - ret = __spufs_proxydma_info_read(ctx, buf, len, pos); > + __spufs_proxydma_info_read(ctx, &info); > + ret = simple_read_from_buffer(buf, len, pos, &info, sizeof(info)); IDGI... What's that access_ok() for? If you are using simple_read_from_buffer(), the damn thing goes through copy_to_user(). Why bother with separate access_ok() here?