From patchwork Sat Nov 7 19:18:35 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anmol Karn X-Patchwork-Id: 322149 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 2BB32C388F7 for ; Sat, 7 Nov 2020 19:18:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D4F84207C3 for ; Sat, 7 Nov 2020 19:18:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="cKqOu8+1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728669AbgKGTSu (ORCPT ); Sat, 7 Nov 2020 14:18:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58100 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725836AbgKGTSu (ORCPT ); Sat, 7 Nov 2020 14:18:50 -0500 Received: from mail-pj1-x1043.google.com (mail-pj1-x1043.google.com [IPv6:2607:f8b0:4864:20::1043]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3454DC0613CF; Sat, 7 Nov 2020 11:18:47 -0800 (PST) Received: by mail-pj1-x1043.google.com with SMTP id g19so562148pji.0; Sat, 07 Nov 2020 11:18:47 -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=cKqOu8+1Y6K1ZqQHZbaNG0Qf/imNxwYLHrCnaYPfjtg1bFR6iCxQqvYVFeJnGgvSDF SHD1/uk84RbB6/LX2Cp8eq56uVvybq5CatnwZBYF+iFaZv3o8SRlFQPxPEHKAbiZqWx+ dgoirOtOQWnq2zloVYRHazX8VP2L3m/5ZoSmzBa1/hOF5+6DFWFPx3k+avt1wRph9uRP bSr4vtdlQmz+I7eQvPVIJhEBjnnzlVYVHXP+iJ0lksy3QfZG80VlXQP/RaIKjc+TlOTG 9Ude7XIsBHDrslUOirvX74P/H+YH9but/0OeYzCR1vqo717iHcxiQ/BydfRmQBMCg+GC c/TA== 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=Iv0/LFpbs33anmySTiMUK3QbDAHuiN9kOr5wIIiKdRpK336dQQgsCHVGWl8H7bSJcv +3wcDdgd3WTkvRgSwQ3MyKyiVB9Gf1cjUuwP9f8SVqcwjv8lq/FnV9EiS2DEAIddLvbI S88l7aw9Oslc77liKs/Dl0Nd768FTkakVNSV3mHH0+JnFwGBtzcVvySQPisJ0dKMCxj6 f/I/uPNXwJ0x+d+qCTbuWzlGFJ2c28BKuDqqgdFDoPNk8D9FiLeVr84hHDcKi1Yx86r+ zo1M7gtkeSFhKaTI9+npD/17ziuYpm5DMKh0TjmvXtcqtE3ayZPGUybutAb3GMOLVCSM Xkeg== X-Gm-Message-State: AOAM530t/jK9hFa0kdvmNdUXKQen4gv0q1M0ltaggU3ui18utx9Hk+xh AoZF8dFUSO/uXVflV4eUudU= X-Google-Smtp-Source: ABdhPJxE68wnEzKKNjlOd4hxH6MSJRj+kJGJIHeajqj0N/aJbNYxh1I6FbCqx4nkEvjGbHzPcNRg2A== X-Received: by 2002:a17:90a:aa89:: with SMTP id l9mr5272232pjq.0.1604776726703; Sat, 07 Nov 2020 11:18:46 -0800 (PST) Received: from localhost.localdomain ([45.118.167.194]) by smtp.googlemail.com with ESMTPSA id r73sm6692020pfc.20.2020.11.07.11.18.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 07 Nov 2020 11:18:45 -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 v3 net] rose: Fix Null pointer dereference in rose_send_frame() Date: Sun, 8 Nov 2020 00:48:35 +0530 Message-Id: <20201107191835.5541-1-anmol.karan123@gmail.com> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201107082041.GA2675@Thinkpad> References: <20201107082041.GA2675@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") 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 {