From patchwork Sat Nov 7 18:56:54 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anmol Karn X-Patchwork-Id: 322150 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=-12.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, 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 901D9C388F7 for ; Sat, 7 Nov 2020 18:57:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 48FCB207C3 for ; Sat, 7 Nov 2020 18:57:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="o7ScU2Xo" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728574AbgKGS5O (ORCPT ); Sat, 7 Nov 2020 13:57:14 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54746 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725836AbgKGS5O (ORCPT ); Sat, 7 Nov 2020 13:57:14 -0500 Received: from mail-pg1-x542.google.com (mail-pg1-x542.google.com [IPv6:2607:f8b0:4864:20::542]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2CC2AC0613CF; Sat, 7 Nov 2020 10:57:14 -0800 (PST) Received: by mail-pg1-x542.google.com with SMTP id z24so3628868pgk.3; Sat, 07 Nov 2020 10:57:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=afHTW824kBEGWvvhUfZ3PFiZzmUwUob7a4RTUq6L29M=; b=o7ScU2Xor+ZuZiG+hPCasydHyXeqbZkNHK3eIs5iVsazHLeSlwETo1FzIG4JhtDPfu 8duzNH3Gvwd+jeqOSOUv8CjLncS0AQ0XShWCAEpqlNonfo9kDYvLrYqqYT+qSiDM7wX9 YZiM3TBqJ7ssVrcBtc7ccbhDYYOvXythStyjRYjxqdWbvg6vpIp4ijSGwUhxUNdAQpU/ 1ssIxh08PjgKPlPKBa7GJT6mtRWkrWNjdXNtauOgBZaW1RukvGhCa9yVPyj51/PRG8Hl Azc0iBK+GRcFrXAN54ENbhsqUUVjp8fQosN0i4gUcaP8JKulxEd3AXwJ07QlarWJKXt8 MBuQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=afHTW824kBEGWvvhUfZ3PFiZzmUwUob7a4RTUq6L29M=; b=MBvh0kqxoTzpV+0MoLJDuIkZ2+gnUOpFhhL8tQfFuTh6T1FA02jZHt2dv2tgPdeFJk CrEeRhCq0NLw6QU+uPphh7gpuZIIKeakoS/QVTMZEENKVEfzMRU922lLG2TpBNLkdM9g 6iRFE1CtBU6GkQGtGjcG4vgR0JYNbP0cOCFj3JBIylp9Wvj3y003SKanUmWOKFBUaPjy UVuUXuTwX6qMbr7BpdHtOSvVUlSlZNA8Hm0Yz8xEMK4x45TLl3q/GNGtSK6Dmdnkj0VT QjRpLugKoH+86GYb1iHLR+ppxuR24wA3hKUSVFapO83Ol7GgCxRn7ANuV8Yje4EDaUXv JuSg== X-Gm-Message-State: AOAM530G86BZxgSIvqw7UbhcU54kc+A2c+iFIrz6zqSSxfcsVYfHSEjb EyjEIzMzpJIpj+sBL/FBBX4= X-Google-Smtp-Source: ABdhPJw2amXadmyF/5X65byZ9X2cW/hVkSb20cYEJFED8+QmCEouNiXV3miVxY+8b3LExk2iYfmWMQ== X-Received: by 2002:a65:6201:: with SMTP id d1mr6502774pgv.156.1604775432941; Sat, 07 Nov 2020 10:57:12 -0800 (PST) Received: from localhost.localdomain ([45.118.167.194]) by smtp.googlemail.com with ESMTPSA id q12sm6738025pfc.84.2020.11.07.10.57.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 07 Nov 2020 10:57:12 -0800 (PST) From: Anmol Karn To: ralf@linux-mips.org, davem@davemloft.net, kuba@kernel.org Cc: saeed@kernel.org, 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, anmol.karan123@gmail.com, syzbot+a1c743815982d9496393@syzkaller.appspotmail.com Subject: [Linux-kernel-mentees] [PATCH v2] net: rose: Fix Null pointer dereference in rose_send_frame() Date: Sun, 8 Nov 2020 00:26:54 +0530 Message-Id: <20201107185654.4339-1-anmol.karan123@gmail.com> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201105155600.9711-1-anmol.karan123@gmail.com> References: <20201105155600.9711-1-anmol.karan123@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org rose_send_frame() dereferences `neigh->dev` when called from rose_transmit_clear_request(), and the first occurrence 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(). Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: syzbot+a1c743815982d9496393@syzkaller.appspotmail.com Tested-by: syzbot+a1c743815982d9496393@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?id=9d2a7ca8c7f2e4b682c97578dfa3f236258300b3 Signed-off-by: Anmol Karn --- Changes in v3: - Corrected checkpatch warnings and errors (Suggested-by: Saeed Mahameed ) - Added "Fixes:" tag (Suggested-by: Saeed Mahameed ) Changes in v2: - Added NULL check in rose_loopback_timer() (Suggested-by: Greg KH ) net/rose/rose_loopback.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) - 2.29.2 diff --git a/net/rose/rose_loopback.c b/net/rose/rose_loopback.c index 7b094275ea8b..2c51756ed7bf 100644 --- a/net/rose/rose_loopback.c +++ b/net/rose/rose_loopback.c @@ -96,7 +96,8 @@ static void rose_loopback_timer(struct timer_list *unused) } if (frametype == ROSE_CALL_REQUEST) { - if ((dev = rose_dev_get(dest)) != NULL) { + dev = rose_dev_get(dest); + if (rose_loopback_neigh->dev && dev) { if (rose_rx_call_request(skb, dev, rose_loopback_neigh, lci_o) == 0) kfree_skb(skb); } else {