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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 478BEC432C0 for ; Wed, 27 Nov 2019 21:25:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1EA96215F1 for ; Wed, 27 Nov 2019 21:25:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574889915; bh=t6h2MdHKYMubMCHj2hQ1lpKMgX+mo2ybIpeMq9ud7/4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Pi6keherEXitUT4d+pIQfQj4kS36H+1N4WB6PnNunxWTAuHeHJVP2kbr4PaqKFDsE xdRvVOwtDyIs3Xzw4rGMjK08z+B9X6rXWZB21NFb9g83ghT8D7BbJTBBnHR1gX6qvg 2/YbAb2RrpgLi7LT9q8E/LxwOgHOgEzo+TQK7nKk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731828AbfK0VCG (ORCPT ); Wed, 27 Nov 2019 16:02:06 -0500 Received: from mail.kernel.org ([198.145.29.99]:54568 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727303AbfK0VCE (ORCPT ); Wed, 27 Nov 2019 16:02:04 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B512D20862; Wed, 27 Nov 2019 21:02:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574888523; bh=t6h2MdHKYMubMCHj2hQ1lpKMgX+mo2ybIpeMq9ud7/4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=z69TRZIaM/U+SCYjEfsm0iUCzXgAOsUK+2gJPxzzPZeVA3Mts4VKqCBbApjbdD0CZ e/sz+vRkogs6StMUyVpVsArA9zPtmlB932tAeWD7q3tekj2nDKHqdteiDreTO2Y0eI /0rC0gNDToWAJFZZWWCAHoEw20modlDE5aKNSVAE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Rasmus Villemoes , Andy Shevchenko , Yury Norov , Sudeep Holla , Andrew Morton , Linus Torvalds , Sasha Levin Subject: [PATCH 4.19 167/306] linux/bitmap.h: handle constant zero-size bitmaps correctly Date: Wed, 27 Nov 2019 21:30:17 +0100 Message-Id: <20191127203127.614192983@linuxfoundation.org> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191127203114.766709977@linuxfoundation.org> References: <20191127203114.766709977@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 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