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=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, 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 97C87C433E0 for ; Mon, 1 Mar 2021 21:25:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 44EB26023C for ; Mon, 1 Mar 2021 21:25:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244189AbhCAVXk (ORCPT ); Mon, 1 Mar 2021 16:23:40 -0500 Received: from mail.kernel.org ([198.145.29.99]:57228 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237987AbhCARQD (ORCPT ); Mon, 1 Mar 2021 12:16:03 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 4B90861606; Mon, 1 Mar 2021 16:46:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1614617176; bh=F3uOmjDRirqlt+F07n7sLAB9NP0IpsyjcYsORllsl2A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=md/xotTxZbPa7/EV779be1vOdENgMqRDP5Ou6cAvvLtmA+uUgqDXA3R4nazP19vTX 4+0k6DsQUkdmSMQGecn0W2B+FKX7olSmIJK2LiQD1mGEaPaCz9B+Jf/O+PhHfzzi7F BsA25SU+o2jqugx03umm8mxSj4sDPO53Zfpt9Dp8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, stable@kernel.org, Al Viro , "David S. Miller" Subject: [PATCH 4.19 230/247] sparc32: fix a user-triggerable oops in clear_user() Date: Mon, 1 Mar 2021 17:14:10 +0100 Message-Id: <20210301161042.956038531@linuxfoundation.org> X-Mailer: git-send-email 2.30.1 In-Reply-To: <20210301161031.684018251@linuxfoundation.org> References: <20210301161031.684018251@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Al Viro commit 7780918b36489f0b2f9a3749d7be00c2ceaec513 upstream. Back in 2.1.29 the clear_user() guts (__bzero()) had been merged with memset(). Unfortunately, while all exception handlers had been copied, one of the exception table entries got lost. As the result, clear_user() starting at 128*n bytes before the end of page and spanning between 8 and 127 bytes into the next page would oops when the second page is unmapped. It's trivial to reproduce - all it takes is main() { int fd = open("/dev/zero", O_RDONLY); char *p = mmap(NULL, 16384, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0); munmap(p + 8192, 8192); read(fd, p + 8192 - 128, 192); } which had been oopsing since March 1997. Says something about the quality of test coverage... ;-/ And while today sparc32 port is nearly dead, back in '97 it had been very much alive; in fact, sparc64 had only been in mainline for 3 months by that point... Cc: stable@kernel.org Fixes: v2.1.29 Signed-off-by: Al Viro Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- arch/sparc/lib/memset.S | 1 + 1 file changed, 1 insertion(+) --- a/arch/sparc/lib/memset.S +++ b/arch/sparc/lib/memset.S @@ -142,6 +142,7 @@ __bzero: ZERO_LAST_BLOCKS(%o0, 0x48, %g2) ZERO_LAST_BLOCKS(%o0, 0x08, %g2) 13: + EXT(12b, 13b, 21f) be 8f andcc %o1, 4, %g0