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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1C195C433F5 for ; Tue, 9 Nov 2021 01:14:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 01FAC610A2 for ; Tue, 9 Nov 2021 01:14:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242373AbhKIBRV (ORCPT ); Mon, 8 Nov 2021 20:17:21 -0500 Received: from mail.kernel.org ([198.145.29.99]:38260 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242324AbhKIBLQ (ORCPT ); Mon, 8 Nov 2021 20:11:16 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8AFD461A85; Tue, 9 Nov 2021 01:04:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1636419890; bh=/pd5iX5CMMG/3ikllfiPRVZXqq7LkR6VQa7ufsfMr2U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fcM1dC73+FOOVoxWC6rpd4OjDl0lJxzgX1N7dNJdfdX4mwp3J3fPgFRAr/MxYfeQu eSZ0dRJbp9O+ea6101iogWHeXaYpxTdGgYm7f7EYLfBqaUQVGNe8ZH8/JGKkHdAV5a ejSPPsVLIS1P/p9Mkki+o40W2/9cqXbNwvUNn9cTu6dwaXd6n3cAjG2zIuFiwE+5ew 45hF3nbmKJnRbtN6R3bBcxWYRFPTUjx//SnG023hxJLhPyVdpqsnkuZa5wOWBTOluk Y1HhWuDeAXPPWi+PNN37MwfAM8u1TSAjbe5SzRaWnkoaGEIQllcb0YZhbnlu6Yh2EA NyRgI/FemlqIQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Pawan Gupta , syzbot+3f91de0b813cc3d19a80@syzkaller.appspotmail.com, Casey Schaufler , Sasha Levin , jmorris@namei.org, serge@hallyn.com, linux-security-module@vger.kernel.org Subject: [PATCH AUTOSEL 5.4 13/74] smackfs: Fix use-after-free in netlbl_catmap_walk() Date: Mon, 8 Nov 2021 12:48:40 -0500 Message-Id: <20211108174942.1189927-13-sashal@kernel.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20211108174942.1189927-1-sashal@kernel.org> References: <20211108174942.1189927-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: From: Pawan Gupta [ Upstream commit 0817534ff9ea809fac1322c5c8c574be8483ea57 ] Syzkaller reported use-after-free bug as described in [1]. The bug is triggered when smk_set_cipso() tries to free stale category bitmaps while there are concurrent reader(s) using the same bitmaps. Wait for RCU grace period to finish before freeing the category bitmaps in smk_set_cipso(). This makes sure that there are no more readers using the stale bitmaps and freeing them should be safe. [1] https://lore.kernel.org/netdev/000000000000a814c505ca657a4e@google.com/ Reported-by: syzbot+3f91de0b813cc3d19a80@syzkaller.appspotmail.com Signed-off-by: Pawan Gupta Signed-off-by: Casey Schaufler Signed-off-by: Sasha Levin --- security/smack/smackfs.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c index 3823ab2c4e4be..cec3f56739dc2 100644 --- a/security/smack/smackfs.c +++ b/security/smack/smackfs.c @@ -831,6 +831,7 @@ static int smk_open_cipso(struct inode *inode, struct file *file) static ssize_t smk_set_cipso(struct file *file, const char __user *buf, size_t count, loff_t *ppos, int format) { + struct netlbl_lsm_catmap *old_cat; struct smack_known *skp; struct netlbl_lsm_secattr ncats; char mapcatset[SMK_CIPSOLEN]; @@ -920,9 +921,11 @@ static ssize_t smk_set_cipso(struct file *file, const char __user *buf, rc = smk_netlbl_mls(maplevel, mapcatset, &ncats, SMK_CIPSOLEN); if (rc >= 0) { - netlbl_catmap_free(skp->smk_netlabel.attr.mls.cat); + old_cat = skp->smk_netlabel.attr.mls.cat; skp->smk_netlabel.attr.mls.cat = ncats.attr.mls.cat; skp->smk_netlabel.attr.mls.lvl = ncats.attr.mls.lvl; + synchronize_rcu(); + netlbl_catmap_free(old_cat); rc = count; } -- 2.33.0