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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 2E8D7C25AED for ; Thu, 2 Sep 2021 06:51:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 109E660F6C for ; Thu, 2 Sep 2021 06:51:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242229AbhIBGwK (ORCPT ); Thu, 2 Sep 2021 02:52:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56134 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239767AbhIBGwI (ORCPT ); Thu, 2 Sep 2021 02:52:08 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 18B4CC061575 for ; Wed, 1 Sep 2021 23:51:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=iKiCgpE2RAx5gME3v9KQAcvDRUxt2sz+SQ5l2zSQS2Y=; b=GSYRQRH3hvmSCEXfuYL6oM6SN2 WwXMxon0LE1dleknLZ37cDxjrlj5tIXIQ0y5a0TuQiTe3BBlou/zaUEsClrBSakAf4IKP+dr0hTv1 4bcZK01UlYAL+IrHPSJenMR1D7xIZj8iRDiZjFHYDfLmy3Xhbje6zNFWHPtJ7FOotT3/x6K64qkrg xWgI85GvDXYnk0KqoTii7gftrem40pFOjj4/JFVGynYv5LAnoOiPp75Yh6a3hOdPmFcZx2WM9h/2U w6bXO+MkBl6TJQF4gP2nAtWTVn41x4lvLkJVmkF3iNqsjEULtGXpBuxqQBdYYBiG41RRdOvUAGtYg ZMaM7NVQ==; Received: from hch by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1mLgXu-003Bjy-DR; Thu, 02 Sep 2021 06:50:08 +0000 Date: Thu, 2 Sep 2021 07:49:58 +0100 From: Christoph Hellwig To: Christophe Leroy Cc: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 1/5] powerpc/signal64: Access function descriptor with user access block Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Aug 23, 2021 at 03:35:51PM +0000, Christophe Leroy wrote: > Access the function descriptor of the handler within a > user access block. > > Signed-off-by: Christophe Leroy > --- > arch/powerpc/kernel/signal_64.c | 14 ++++++++++++-- > 1 file changed, 12 insertions(+), 2 deletions(-) > > diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c > index 1831bba0582e..790c450c2de8 100644 > --- a/arch/powerpc/kernel/signal_64.c > +++ b/arch/powerpc/kernel/signal_64.c > @@ -936,8 +936,18 @@ int handle_rt_signal64(struct ksignal *ksig, sigset_t *set, > func_descr_t __user *funct_desc_ptr = > (func_descr_t __user *) ksig->ka.sa.sa_handler; > > - err |= get_user(regs->ctr, &funct_desc_ptr->entry); > - err |= get_user(regs->gpr[2], &funct_desc_ptr->toc); > + if (user_read_access_begin(funct_desc_ptr, sizeof(func_descr_t))) { > + unsafe_get_user(regs->ctr, &funct_desc_ptr->entry, bad_funct_desc_block); > + unsafe_get_user(regs->gpr[2], &funct_desc_ptr->toc, bad_funct_desc_block); > + } else { > + goto bad_funct_desc; > +bad_funct_desc_block: > + user_read_access_end(); > +bad_funct_desc: > + signal_fault(current, regs, __func__, funct_desc_ptr); > + return 1; > + } > + user_read_access_end(); Having a goto after an ele block, an then labels jumping into it is just weird. To make this somewhat readable just split it into a helper function: static inline bool put_func_descr(func_descr_t __user *funct_desc_ptr, struct pt_regs *regs) { if (!user_read_access_begin(funct_desc_ptr, sizeof(func_descr_t))) goto fault; unsafe_get_user(regs->ctr, &funct_desc_ptr->entry, uaccess_end); unsafe_get_user(regs->gpr[2], &funct_desc_ptr->toc, uaccess_end); user_read_access_end(); return false; uaccess_end: user_read_access_end(); fault: signal_fault(current, regs, __func__, funct_desc_ptr); return true; }