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=-10.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 2ECD5C5517A for ; Fri, 6 Nov 2020 21:04:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CD210208C7 for ; Fri, 6 Nov 2020 21:04:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604696674; bh=9ixnt+Fdr/ysIEkQIJWSwlXkjcUJXvNSmNtHjsiEvhE=; h=Subject:From:To:Cc:Date:In-Reply-To:References:List-ID:From; b=pKdJDeP32PIg2rRRLY8rz19S142KL3nWiJtya8dHiE+5Lk2hUnq2IVRch+ICpdj88 hZyCunvWuwweD1KfIlCrHritOSjFbMQ37eKn65RnbNgyhhJX9tJ22o+ejO6NM2F0r0 ewiSZp4MSeZ44xq9gP0a5fOR18DGGS5dNmTGyFvI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728564AbgKFVEa (ORCPT ); Fri, 6 Nov 2020 16:04:30 -0500 Received: from mail.kernel.org ([198.145.29.99]:44874 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728496AbgKFVEa (ORCPT ); Fri, 6 Nov 2020 16:04:30 -0500 Received: from sx1.lan (c-24-6-56-119.hsd1.ca.comcast.net [24.6.56.119]) (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 C6B8B2087E; Fri, 6 Nov 2020 21:04:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604696669; bh=9ixnt+Fdr/ysIEkQIJWSwlXkjcUJXvNSmNtHjsiEvhE=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=KFTHiXojtHgyof51PtRWCwBIRcqkJ1S5Phui0j1JLOLZBxMx9HmFYeI/5gMMBWsex M1ZDm8to6GsjbAV8O9qJrgK/fj+NIBURT3UjpSq0oIcxcuHEiVF4ikFxFNt3TjXbGh E17KJbrxv5tFIDQVMGAUmX9a+ESyjLPd/kFKIWgc= Message-ID: Subject: Re: [Linux-kernel-mentees] [PATCH v2 net] rose: Fix Null pointer dereference in rose_send_frame() From: Saeed Mahameed To: Anmol Karn , ralf@linux-mips.org, davem@davemloft.net, kuba@kernel.org Cc: gregkh@linuxfoundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hams@vger.kernel.org, linux-kernel-mentees@lists.linuxfoundation.org, syzkaller-bugs@googlegroups.com, syzbot+a1c743815982d9496393@syzkaller.appspotmail.com Date: Fri, 06 Nov 2020 13:04:27 -0800 In-Reply-To: <20201105155600.9711-1-anmol.karan123@gmail.com> References: <20201105155600.9711-1-anmol.karan123@gmail.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-1.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu, 2020-11-05 at 21:26 +0530, Anmol Karn wrote: > rose_send_frame() dereferences `neigh->dev` when called from > rose_transmit_clear_request(), and the first occurance of the `neigh` > is in rose_loopback_timer() as `rose_loopback_neigh`, and it is > initialized > in rose_add_loopback_neigh() as NULL. i.e when `rose_loopback_neigh` > used in > rose_loopback_timer() its `->dev` was still NULL and > rose_loopback_timer() > was calling rose_rx_call_request() without checking for NULL. > > - net/rose/rose_link.c > This bug seems to get triggered in this line: > > rose_call = (ax25_address *)neigh->dev->dev_addr; > > Fix it by adding NULL checking for `rose_loopback_neigh->dev` in > rose_loopback_timer(). > > Reported-and-tested-by: > syzbot+a1c743815982d9496393@syzkaller.appspotmail.com > Link: > https://syzkaller.appspot.com/bug?id=9d2a7ca8c7f2e4b682c97578dfa3f236258300b3 > > Signed-off-by: Anmol Karn missing proper fixes tag. > --- > net/rose/rose_loopback.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/net/rose/rose_loopback.c b/net/rose/rose_loopback.c > index 7b094275ea8b..cd7774cb1d07 100644 > --- a/net/rose/rose_loopback.c > +++ b/net/rose/rose_loopback.c > @@ -96,7 +96,7 @@ static void rose_loopback_timer(struct timer_list > *unused) > } > > if (frametype == ROSE_CALL_REQUEST) { > - if ((dev = rose_dev_get(dest)) != NULL) { > + if (rose_loopback_neigh->dev && (dev = > rose_dev_get(dest)) != NULL) { > if (rose_rx_call_request(skb, dev, > rose_loopback_neigh, lci_o) == 0) > kfree_skb(skb); > } else { check patch is not happy: WARNING:TYPO_SPELLING: 'occurance' may be misspelled - perhaps 'occurrence'? #7: rose_transmit_clear_request(), and the first occurance of the `neigh` ERROR:ASSIGN_IN_IF: do not use assignment in if condition #36: FILE: net/rose/rose_loopback.c:99: + if (rose_loopback_neigh->dev && (dev = rose_dev_get(dest)) != NULL) { total: 1 errors, 1 warnings, 0 checks, 8 lines checked