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 29AEFC4332F for ; Tue, 9 Nov 2021 01:31:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 119DA611BF for ; Tue, 9 Nov 2021 01:31:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242375AbhKIBdR (ORCPT ); Mon, 8 Nov 2021 20:33:17 -0500 Received: from mail.kernel.org ([198.145.29.99]:49932 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244162AbhKIBYx (ORCPT ); Mon, 8 Nov 2021 20:24:53 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id A390F61B3E; Tue, 9 Nov 2021 01:09:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1636420170; bh=R+InoCmYe1125Ct1qO4aIFakey8YpbsTDyv9iDEBhi8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jb6cM6Kp/lAhAQXudUl7wfg3Dgi9G1b/gHFjTG55xF8+EFM0U1+/nJYmb5PfrEUgg HzihbC4mdKXU3Xe6h3nLMJgBWlJ3AYjNtwQycSSsfiVyRm5INPERSxdomoTrISE9yF gEVE5DE5YzkIxxOmzwvaaAIvPu21VnpMfYbgsHKFWnC7J0Zbf9yp4lgBzea5R9QeyE kNS6jJ7hOGpdR6H1cmgeBiUVzQqxNdT1U6/qkGNR1tMGK800b+LWQjSrWr9m/KrXX3 02TIYgNYiHndLOv90cehrLIWfRMQnhQudbjoo0zIpNkzGUG8kRz/QeugHLy8wet6g6 i43JrrfOrBXmg== 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 4.4 06/30] smackfs: Fix use-after-free in netlbl_catmap_walk() Date: Mon, 8 Nov 2021 20:08:54 -0500 Message-Id: <20211109010918.1192063-6-sashal@kernel.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20211109010918.1192063-1-sashal@kernel.org> References: <20211109010918.1192063-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 df082648eb0aa..845ed464fb8cd 100644 --- a/security/smack/smackfs.c +++ b/security/smack/smackfs.c @@ -859,6 +859,7 @@ 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]; @@ -952,9 +953,11 @@ 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