From patchwork Mon Mar 13 22:12:31 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 13173384 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 867BDC6FD19 for ; Mon, 13 Mar 2023 22:15:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229899AbjCMWPD (ORCPT ); Mon, 13 Mar 2023 18:15:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54644 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229880AbjCMWPB (ORCPT ); Mon, 13 Mar 2023 18:15:01 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [IPv6:2604:1380:40e1:4800::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A32DD67034; Mon, 13 Mar 2023 15:14:59 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id 23BCFCE125A; Mon, 13 Mar 2023 22:14:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3E58BC4339C; Mon, 13 Mar 2023 22:14:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1678745696; bh=vw79fexAzk+yE0svCHr1v/BgnaY2Tly6xl5VXbAiZhw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LK6JKHs6m9sUCerh7e5n//h20BLNUyW/1NH6LLDt4oCBFJ18lLsJAtst3HYsL6uXH fNmdLHDgNVj0nU9wLa9f5lq+1yWgl9nr3s6e5KCpGMSPJw+gvw9fKtaUIkEEhbAFfD ABqnLHHxLNzjRHeOD9721NfZVDsvuyZno0deDky7oPxSiSgIEldJxEnhTlv1+HQX1u XGqVm4Hn1t9DSYxR8gGod3Sk66w1ZkGAhGkPsZzG6lmBDXef8T2WzKQfty5L3HrQyg 54gJyMdwcu3Vd3+MxjXkP3mhABw/jpoOxrm0YhpS09XBWO4HerjCUgard6W4OaTDOs fCNnL60d9i01g== From: Eric Biggers To: linux-fscrypt@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org Subject: [PATCH 3/3] fscrypt: check for NULL keyring in fscrypt_put_master_key_activeref() Date: Mon, 13 Mar 2023 15:12:31 -0700 Message-Id: <20230313221231.272498-4-ebiggers@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230313221231.272498-1-ebiggers@kernel.org> References: <20230313221231.272498-1-ebiggers@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: Eric Biggers It is a bug for fscrypt_put_master_key_activeref() to see a NULL keyring. But it used to be possible due to the bug, now fixed, where fscrypt_destroy_keyring() was called before security_sb_delete(). To be consistent with how fscrypt_destroy_keyring() uses WARN_ON for the same issue, WARN and leak the fscrypt_master_key if the keyring is NULL instead of dereferencing the NULL pointer. This is a robustness improvement, not a fix. Signed-off-by: Eric Biggers --- fs/crypto/keyring.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/crypto/keyring.c b/fs/crypto/keyring.c index bb15709ac9a40..13d336a6cc5da 100644 --- a/fs/crypto/keyring.c +++ b/fs/crypto/keyring.c @@ -92,6 +92,8 @@ void fscrypt_put_master_key_activeref(struct super_block *sb, * destroying any subkeys embedded in it. */ + if (WARN_ON(!sb->s_master_keys)) + return; spin_lock(&sb->s_master_keys->lock); hlist_del_rcu(&mk->mk_node); spin_unlock(&sb->s_master_keys->lock);