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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 1BED7C49ED7 for ; Thu, 19 Sep 2019 22:11:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E104321924 for ; Thu, 19 Sep 2019 22:11:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1568931075; bh=e1h3js1akksNSdN7MbHfoSgbNrAbeyQ3zCDjASU0y00=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Mgy1+0i6JB4aERhvvc3u0dfYjTIqO40YKnMA9v87jz6B2nUHPsMjPPnIBNBAPG3EJ Kalfjn7PDnbx7mZhDYUF8z064YxGLyKLMFwXvWCxquMcmbZs3oLKy5Q6AFP6Xw4GAm JePCSC8FmoiZG+S+iBqSceQSRTooGCaUzN6UPjUE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2393548AbfISWLO (ORCPT ); Thu, 19 Sep 2019 18:11:14 -0400 Received: from mail.kernel.org ([198.145.29.99]:49794 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391186AbfISWLJ (ORCPT ); Thu, 19 Sep 2019 18:11:09 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 6AE5521927; Thu, 19 Sep 2019 22:11:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1568931068; bh=e1h3js1akksNSdN7MbHfoSgbNrAbeyQ3zCDjASU0y00=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SgavgBn6F/7EvhQQiRQybiyBm1/oOs8i/v2f4imx1Mj6X3xDfmgSzROh6yDCogz1g a8VF+xqiqfDjzULcTt11YJkCtzITAh49TtDLmV4Ac9YfyjiAaFHkJMfj5EfmvI8tTO mvOh0OzBdim3L5shM71IrLRoluntWSKmPX/fmCt0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sachin Sant , Hillf Danton , David Howells , Linus Torvalds , Sasha Levin Subject: [PATCH 5.2 117/124] keys: Fix missing null pointer check in request_key_auth_describe() Date: Fri, 20 Sep 2019 00:03:25 +0200 Message-Id: <20190919214823.437246809@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20190919214819.198419517@linuxfoundation.org> References: <20190919214819.198419517@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Hillf Danton [ Upstream commit d41a3effbb53b1bcea41e328d16a4d046a508381 ] If a request_key authentication token key gets revoked, there's a window in which request_key_auth_describe() can see it with a NULL payload - but it makes no check for this and something like the following oops may occur: BUG: Kernel NULL pointer dereference at 0x00000038 Faulting instruction address: 0xc0000000004ddf30 Oops: Kernel access of bad area, sig: 11 [#1] ... NIP [...] request_key_auth_describe+0x90/0xd0 LR [...] request_key_auth_describe+0x54/0xd0 Call Trace: [...] request_key_auth_describe+0x54/0xd0 (unreliable) [...] proc_keys_show+0x308/0x4c0 [...] seq_read+0x3d0/0x540 [...] proc_reg_read+0x90/0x110 [...] __vfs_read+0x3c/0x70 [...] vfs_read+0xb4/0x1b0 [...] ksys_read+0x7c/0x130 [...] system_call+0x5c/0x70 Fix this by checking for a NULL pointer when describing such a key. Also make the read routine check for a NULL pointer to be on the safe side. [DH: Modified to not take already-held rcu lock and modified to also check in the read routine] Fixes: 04c567d9313e ("[PATCH] Keys: Fix race between two instantiators of a key") Reported-by: Sachin Sant Signed-off-by: Hillf Danton Signed-off-by: David Howells Tested-by: Sachin Sant Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- security/keys/request_key_auth.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/security/keys/request_key_auth.c b/security/keys/request_key_auth.c index e45b5cf3b97fd..8491becb57270 100644 --- a/security/keys/request_key_auth.c +++ b/security/keys/request_key_auth.c @@ -66,6 +66,9 @@ static void request_key_auth_describe(const struct key *key, { struct request_key_auth *rka = get_request_key_auth(key); + if (!rka) + return; + seq_puts(m, "key:"); seq_puts(m, key->description); if (key_is_positive(key)) @@ -83,6 +86,9 @@ static long request_key_auth_read(const struct key *key, size_t datalen; long ret; + if (!rka) + return -EKEYREVOKED; + datalen = rka->callout_len; ret = datalen; -- 2.20.1