From patchwork Thu Nov 19 19:10:43 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anmol Karn X-Patchwork-Id: 1403225 Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20161025 header.b=M9O64TUO; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4CcTmc2kG3z9sVJ for ; Fri, 20 Nov 2020 06:11:12 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727955AbgKSTLB (ORCPT ); Thu, 19 Nov 2020 14:11:01 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51010 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727240AbgKSTLA (ORCPT ); Thu, 19 Nov 2020 14:11:00 -0500 Received: from mail-pg1-x544.google.com (mail-pg1-x544.google.com [IPv6:2607:f8b0:4864:20::544]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8B311C0613CF; Thu, 19 Nov 2020 11:11:00 -0800 (PST) Received: by mail-pg1-x544.google.com with SMTP id 34so5076919pgp.10; Thu, 19 Nov 2020 11:11:00 -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=ET473FpFp3FzmBYHYLYam48z0xHPg334N2d9XOKTrpI=; b=M9O64TUOsf61++A5YWBgorUTqsUhConEUSLgnhF2hmpRoMo9gbHMK0Y5lS02yWOQMn xrFztSbuLNQ+ucnJjCg73QRIECuWEG+UR2GOfVP2Mi+rJVZf9I83c8TB9KF9Mx0DCQIA S5xL24QjlB8rFTuwVcmUY0UFBOak89hVYYiTrzQTOcOr09VZvuHUqOPNvaTHx/uOSWzr y5ZKb595uyBSpRpNI0CZNInd4rqqkQmzLNBTRx/yGjwDlJzPes7Gmth90pGXMZKrnfRh FJxt8mxU95GAFuC0N0CG+/whmIcWoGZUPxlmWUy8+JWcC8kzHnkSMrOxTotefn/d24i1 cF5Q== 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=ET473FpFp3FzmBYHYLYam48z0xHPg334N2d9XOKTrpI=; b=saAL8lAtYi9pQyFFS6FlAAtdo6kJfCBBe1ZknAiZoZkhnxBCA1AnNXThFI+yssJzfv nie7tHjvDJFLXkji5J9pMvxf+LmOEwS0xi0sNsZ8+YtCeiIR+XYHnj1Fqf1JHFlLtX+c I0McBcdWFDBdyyDGbCLGosK6mZF9hBkD72CBzIJYCAvGg7a+lA3gCXiZvdaoIhZIi1lw J2RQfQ1t96oMqufph44q2zuq/LeZQJKotdFy/erQDLVDNSV8a/trNeqscLaJzopMgRkt 90COlAU75tWqfIN8K5S6gcgKPwjwlrz3pDZL0uKndNoPVi8ev4ebwBI39c5m/i9WMbnV i6kg== X-Gm-Message-State: AOAM530G382UljjIs/IMy6k8o9j4eFS/0LfE5kQujf94ggrf4ZaI6XSn RrXl6Aetj0XpePhuNJj+RC0= X-Google-Smtp-Source: ABdhPJypWIrTZZnDbwimuxmJITaEMB9QJgxNpUGeZf5bAuv3w+zqFXccFDnDvw5F0qjTUHsJf5qQlQ== X-Received: by 2002:aa7:8105:0:b029:18e:c8d9:2c24 with SMTP id b5-20020aa781050000b029018ec8d92c24mr10267432pfi.49.1605813059959; Thu, 19 Nov 2020 11:10:59 -0800 (PST) Received: from localhost.localdomain ([45.118.167.196]) by smtp.googlemail.com with ESMTPSA id x3sm452245pjk.17.2020.11.19.11.10.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 19 Nov 2020 11:10:58 -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 v5 net] rose: Fix Null pointer dereference in rose_send_frame() Date: Fri, 20 Nov 2020 00:40:43 +0530 Message-Id: <20201119191043.28813-1-anmol.karan123@gmail.com> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201115114448.GA40574@Thinkpad> References: <20201115114448.GA40574@Thinkpad> 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") Suggested-by: Jakub Kicinski 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 v5: - Free `dev` in rose_rx_call_request() and add NULL check for `dev` before freeing it. (Suggested-by: Jakub Kicinski ) Changes in v4: - Free `dev`(on dev_hold()), when neigh->dev is NULL. (Suggested-by: Jakub Kicinski ) 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 | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) -- 2.29.2 diff --git a/net/rose/rose_loopback.c b/net/rose/rose_loopback.c index 7b094275ea8b..11c45c8c6c16 100644 --- a/net/rose/rose_loopback.c +++ b/net/rose/rose_loopback.c @@ -96,10 +96,19 @@ static void rose_loopback_timer(struct timer_list *unused) } if (frametype == ROSE_CALL_REQUEST) { - if ((dev = rose_dev_get(dest)) != NULL) { - if (rose_rx_call_request(skb, dev, rose_loopback_neigh, lci_o) == 0) - kfree_skb(skb); - } else { + if (!rose_loopback_neigh->dev) { + kfree_skb(skb); + continue; + } + + dev = rose_dev_get(dest); + if (!dev) { + kfree_skb(skb); + continue; + } + + if (rose_rx_call_request(skb, dev, rose_loopback_neigh, lci_o) == 0) { + dev_put(dev); kfree_skb(skb); } } else {