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=-3.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 26455C2BA1A for ; Tue, 7 Apr 2020 03:12:11 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E1797206B8 for ; Tue, 7 Apr 2020 03:12:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="LU1J0DkA" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E1797206B8 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 8F1798E009F; Mon, 6 Apr 2020 23:12:10 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8CBD38E0062; Mon, 6 Apr 2020 23:12:10 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7DE918E009F; Mon, 6 Apr 2020 23:12:10 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0230.hostedemail.com [216.40.44.230]) by kanga.kvack.org (Postfix) with ESMTP id 606598E0062 for ; Mon, 6 Apr 2020 23:12:10 -0400 (EDT) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 29D048017CA0 for ; Tue, 7 Apr 2020 03:12:10 +0000 (UTC) X-FDA: 76679585220.10.toad13_12e82f027c34e X-HE-Tag: toad13_12e82f027c34e X-Filterd-Recvd-Size: 3603 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf36.hostedemail.com (Postfix) with ESMTP for ; Tue, 7 Apr 2020 03:12:09 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (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 C2AA02072F; Tue, 7 Apr 2020 03:12:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586229129; bh=ClzcHm/95YALvuptWuiQCuSErlEuhpYPPr4nMsmD9Xk=; h=Date:From:To:Subject:In-Reply-To:From; b=LU1J0DkAR7qqWBZ9T0GI2/5NAiqPEq+gDLl5hKZKIRNb+rrMLXUgAyTB3ExLQvekp hfjqJ1WZYqRRPPdP2ozQRhyckTs2/Vtwojq9svvLdNqhQytJwmgCMdphh1HjG9y51J aWLCGEZnTnuAkLJFh7VgRl2MIs/HgW6jq2pC/yVg= Date: Mon, 06 Apr 2020 20:12:08 -0700 From: Andrew Morton To: akpm@linux-foundation.org, andreyknvl@gmail.com, andreyknvl@google.com, elver@google.com, glider@google.com, gregkh@linuxfoundation.org, linux-mm@kvack.org, mm-commits@vger.kernel.org, stern@rowland.harvard.edu, torvalds@linux-foundation.org Subject: [patch 152/166] kcov: fix potential use-after-free in kcov_remote_start Message-ID: <20200407031208.wsYgOelp4%akpm@linux-foundation.org> In-Reply-To: <20200406200254.a69ebd9e08c4074e41ddebaf@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Andrey Konovalov Subject: kcov: fix potential use-after-free in kcov_remote_start If vmalloc() fails in kcov_remote_start() we'll access remote->kcov without holding kcov_remote_lock, so remote might potentially be freed at that point. Cache kcov pointer in a local variable. Link: http://lkml.kernel.org/r/9d9134359725a965627b7e8f2652069f86f1d1fa.1585233617.git.andreyknvl@google.com Link: http://lkml.kernel.org/r/de0d3d30ff90776a2a509cc34c7c1c7521bda125.1584655448.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Cc: Alan Stern Cc: Alexander Potapenko Cc: Greg Kroah-Hartman Cc: Marco Elver Cc: Andrey Konovalov Signed-off-by: Andrew Morton --- kernel/kcov.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) --- a/kernel/kcov.c~kcov-fix-potential-use-after-free-in-kcov_remote_start +++ a/kernel/kcov.c @@ -748,6 +748,7 @@ static const struct file_operations kcov void kcov_remote_start(u64 handle) { struct kcov_remote *remote; + struct kcov *kcov; void *area; struct task_struct *t; unsigned int size; @@ -774,16 +775,17 @@ void kcov_remote_start(u64 handle) spin_unlock(&kcov_remote_lock); return; } + kcov = remote->kcov; /* Put in kcov_remote_stop(). */ - kcov_get(remote->kcov); - t->kcov = remote->kcov; + kcov_get(kcov); + t->kcov = kcov; /* * Read kcov fields before unlock to prevent races with * KCOV_DISABLE / kcov_remote_reset(). */ - size = remote->kcov->remote_size; - mode = remote->kcov->mode; - sequence = remote->kcov->sequence; + size = kcov->remote_size; + mode = kcov->mode; + sequence = kcov->sequence; area = kcov_remote_area_get(size); spin_unlock(&kcov_remote_lock); @@ -791,7 +793,7 @@ void kcov_remote_start(u64 handle) area = vmalloc(size * sizeof(unsigned long)); if (!area) { t->kcov = NULL; - kcov_put(remote->kcov); + kcov_put(kcov); return; } } _