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=-19.1 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, URIBL_BLOCKED,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 684E0C4320E for ; Wed, 1 Sep 2021 12:35:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 54750610CF for ; Wed, 1 Sep 2021 12:35:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343775AbhIAMge (ORCPT ); Wed, 1 Sep 2021 08:36:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:33492 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343873AbhIAMeh (ORCPT ); Wed, 1 Sep 2021 08:34:37 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 6429B6101B; Wed, 1 Sep 2021 12:32:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1630499562; bh=1qwlMTCwX3PCcmkFnA7S1Z4+zxtyGF4FyrniO142TGU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BRmK+OIZmRmK7S9qHC3A447dtnXZxPY43EjBVvN8Su0HdIhy9WwBDNxyT6SPu4ISJ mVRoVSmGLgHD0veKWNhstdBOtXMHZA1IoDkuTmt7jRi1BDOYmToIOve+JF6hCK4Xe6 RbTlob+hZwSJ60IsUDpxc3LUqMIjnGbUoriyvBFI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jan Kara , Will Deacon , Alexander Viro , Seiji Nishikawa , Richard Guy Briggs , Paul Moore Subject: [PATCH 5.4 48/48] audit: move put_tree() to avoid trim_trees refcount underflow and UAF Date: Wed, 1 Sep 2021 14:28:38 +0200 Message-Id: <20210901122254.957547573@linuxfoundation.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20210901122253.388326997@linuxfoundation.org> References: <20210901122253.388326997@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: Richard Guy Briggs commit 67d69e9d1a6c889d98951c1d74b19332ce0565af upstream. AUDIT_TRIM is expected to be idempotent, but multiple executions resulted in a refcount underflow and use-after-free. git bisect fingered commit fb041bb7c0a9 ("locking/refcount: Consolidate implementations of refcount_t") but this patch with its more thorough checking that wasn't in the x86 assembly code merely exposed a previously existing tree refcount imbalance in the case of tree trimming code that was refactored with prune_one() to remove a tree introduced in commit 8432c7006297 ("audit: Simplify locking around untag_chunk()") Move the put_tree() to cover only the prune_one() case. Passes audit-testsuite and 3 passes of "auditctl -t" with at least one directory watch. Cc: Jan Kara Cc: Will Deacon Cc: Alexander Viro Cc: Seiji Nishikawa Cc: stable@vger.kernel.org Fixes: 8432c7006297 ("audit: Simplify locking around untag_chunk()") Signed-off-by: Richard Guy Briggs Reviewed-by: Jan Kara [PM: reformatted/cleaned-up the commit description] Signed-off-by: Paul Moore Signed-off-by: Greg Kroah-Hartman --- kernel/audit_tree.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/kernel/audit_tree.c +++ b/kernel/audit_tree.c @@ -595,7 +595,6 @@ static void prune_tree_chunks(struct aud spin_lock(&hash_lock); } spin_unlock(&hash_lock); - put_tree(victim); } /* @@ -604,6 +603,7 @@ static void prune_tree_chunks(struct aud static void prune_one(struct audit_tree *victim) { prune_tree_chunks(victim, false); + put_tree(victim); } /* trim the uncommitted chunks from tree */