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 5F8DCC3A5A6 for ; Thu, 19 Sep 2019 22:27:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3475020640 for ; Thu, 19 Sep 2019 22:27:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1568932042; bh=eArGvEepIIpMO6s2toapya3rfKhfxPzPCS9EURu4A60=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=17oQp/VkETkBZWuTN4zQjAnjN6IpJVRODw7vkeApWFYKRZ/GvMetS/taKm5nFzIGZ 28n5f8BEmlvWEzOGDZZTBu1ceSxEkvtCYiZyUR44qVo7goIgLA5CPohh8co/lKx3Uu vm77+i0szEHdrowvq/g+sAVglBvVosFegnZ2JCuI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2406144AbfISW1V (ORCPT ); Thu, 19 Sep 2019 18:27:21 -0400 Received: from mail.kernel.org ([198.145.29.99]:35580 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2406680AbfISWVK (ORCPT ); Thu, 19 Sep 2019 18:21:10 -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 B6DAF21924; Thu, 19 Sep 2019 22:21:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1568931670; bh=eArGvEepIIpMO6s2toapya3rfKhfxPzPCS9EURu4A60=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LJV5E5q+RKxS01iC6/FyfxC1ng7GWIN0FH0J8QrrdnuUkQaJPbUJgntUzlRjv9qk9 m/MilsUIPUfPkLhXtljVIh770Xa70MWGigXL/MRrxrCK1kktqA4R2H39pJdVuF4x// lSSASey0gBGFERxKHua/LPN+VqRepGxtUWZopw/s= 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 4.9 70/74] keys: Fix missing null pointer check in request_key_auth_describe() Date: Fri, 20 Sep 2019 00:04:23 +0200 Message-Id: <20190919214811.184544234@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20190919214800.519074117@linuxfoundation.org> References: <20190919214800.519074117@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 f60baeb338e5f..b47445022d5ce 100644 --- a/security/keys/request_key_auth.c +++ b/security/keys/request_key_auth.c @@ -71,6 +71,9 @@ static void request_key_auth_describe(const struct key *key, { struct request_key_auth *rka = key->payload.data[0]; + if (!rka) + return; + seq_puts(m, "key:"); seq_puts(m, key->description); if (key_is_positive(key)) @@ -88,6 +91,9 @@ 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