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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 107EFC43215 for ; Sat, 16 Nov 2019 15:44:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DD36020740 for ; Sat, 16 Nov 2019 15:44:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573919096; bh=t6h2MdHKYMubMCHj2hQ1lpKMgX+mo2ybIpeMq9ud7/4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=FMlgEYXSmvopM8I9gamFc70DLaZs39nh4bEJt03HzUrYEM8/bQRyBmqEsVkJhTJje pD9AoOA1cPWZpOZEvgWN0U41FmRuj9fyiGESS1LLbvfG8puYBRH89gXNqBgIMeY/YG J49N5Caoiw2f8eBPH3eOX74LJdD2youIZKU04atc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729094AbfKPPoz (ORCPT ); Sat, 16 Nov 2019 10:44:55 -0500 Received: from mail.kernel.org ([198.145.29.99]:49970 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729079AbfKPPou (ORCPT ); Sat, 16 Nov 2019 10:44:50 -0500 Received: from sasha-vm.mshome.net (unknown [50.234.116.4]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 92C622073B; Sat, 16 Nov 2019 15:44:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573919090; bh=t6h2MdHKYMubMCHj2hQ1lpKMgX+mo2ybIpeMq9ud7/4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cU+8BEq6qUyV3CbG8xn0gb5AfXUPLovrAe+rSkrRyYrWP1PDyzLMyuLuYmFWsXZlO 01ckk2tTZRTXMzNNEymaWmhOJnirlPmDL6dgspTFrVpwuh4UhdVC5bovVVZegHMYRN ucV/7Ey1ujTm2AZjhR8Kzbrv/KKpIw6zZ732tZ3A= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Rasmus Villemoes , Andy Shevchenko , Yury Norov , Sudeep Holla , Andrew Morton , Linus Torvalds , Sasha Levin Subject: [PATCH AUTOSEL 4.19 150/237] linux/bitmap.h: handle constant zero-size bitmaps correctly Date: Sat, 16 Nov 2019 10:39:45 -0500 Message-Id: <20191116154113.7417-150-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191116154113.7417-1-sashal@kernel.org> References: <20191116154113.7417-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Rasmus Villemoes [ Upstream commit 7275b097851a5e2e0dd4da039c7e96b59ac5314e ] The static inlines in bitmap.h do not handle a compile-time constant nbits==0 correctly (they dereference the passed src or dst pointers, despite only 0 words being valid to access). I had the 0-day buildbot chew on a patch [1] that would cause build failures for such cases without complaining, suggesting that we don't have any such users currently, at least for the 70 .config/arch combinations that was built. Should any turn up, make sure they use the out-of-line versions, which do handle nbits==0 correctly. This is of course not the most efficient, but it's much less churn than teaching all the static inlines an "if (zero_const_nbits())", and since we don't have any current instances, this doesn't affect existing code at all. [1] lkml.kernel.org/r/20180815085539.27485-1-linux@rasmusvillemoes.dk Link: http://lkml.kernel.org/r/20180818131623.8755-3-linux@rasmusvillemoes.dk Signed-off-by: Rasmus Villemoes Reviewed-by: Andy Shevchenko Cc: Yury Norov Cc: Rasmus Villemoes Cc: Sudeep Holla Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- include/linux/bitmap.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h index acf5e8df3504f..a9805bacbd7ca 100644 --- a/include/linux/bitmap.h +++ b/include/linux/bitmap.h @@ -204,8 +204,13 @@ extern int bitmap_print_to_pagebuf(bool list, char *buf, #define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) & (BITS_PER_LONG - 1))) #define BITMAP_LAST_WORD_MASK(nbits) (~0UL >> (-(nbits) & (BITS_PER_LONG - 1))) +/* + * The static inlines below do not handle constant nbits==0 correctly, + * so make such users (should any ever turn up) call the out-of-line + * versions. + */ #define small_const_nbits(nbits) \ - (__builtin_constant_p(nbits) && (nbits) <= BITS_PER_LONG) + (__builtin_constant_p(nbits) && (nbits) <= BITS_PER_LONG && (nbits) > 0) static inline void bitmap_zero(unsigned long *dst, unsigned int nbits) { -- 2.20.1