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=-12.5 required=3.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED,DKIM_INVALID,DKIM_SIGNED,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=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 83BA4C433DF for ; Fri, 9 Oct 2020 16:17:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 465EE2227F for ; Fri, 9 Oct 2020 16:17:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="cPgy8ppf" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389661AbgJIQRM (ORCPT ); Fri, 9 Oct 2020 12:17:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42066 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389410AbgJIQRL (ORCPT ); Fri, 9 Oct 2020 12:17:11 -0400 Received: from mail-pl1-x644.google.com (mail-pl1-x644.google.com [IPv6:2607:f8b0:4864:20::644]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 616A4C0613D2 for ; Fri, 9 Oct 2020 09:17:11 -0700 (PDT) Received: by mail-pl1-x644.google.com with SMTP id bb1so4681719plb.2 for ; Fri, 09 Oct 2020 09:17:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=Bmx9gH8QKYILpVv8/AwBKiqUZ1W2aX/bT7meRLse05U=; b=cPgy8ppfUqoug6Hor5S2QVmhFZWHFrqJXMkkIlCfoLjsNgIXVupZCDSidSxzpRprlj rfjpDWTuGxujG0WGnuwCUd6DtrIqIe0Q4piEXyARszAGEaARe7MERlHX28vBE6rjBXwn wmM+lgmATC9rUzbL/+UIHkSlNXi/qBUfCT9r6Mi6QAD4XJCyy6XEmUsTKED84w+Y3gj3 8j/Y8BiwF6GBByc7N15bCx8BOlnz2THm/VCh31ARuX6A4D//SleD+C8Zo0UXPmgVQdBI mMt4n+Q+5NQjk4XxRrSDeY/BaUvWQymMw6xAi760bKR2bgDfqkEBy2f7SpGyHP+Vad6P l0PA== 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:mime-version :content-transfer-encoding; bh=Bmx9gH8QKYILpVv8/AwBKiqUZ1W2aX/bT7meRLse05U=; b=r1TpF7/OYFNfHbrqHs0e3rJ7ouaxe2SCB9gil8Yx4vBJJCLIqsqxjZMzz+dBomQ0h/ KfvjZaihKH8pmjJAiew5z2OvigUesKaLpHaE6bn6MR+XC2wBFUmMcG5PJFdlAMhVcCsa SI3H4KvokbpC/10xWU3b/zv0KhhktfdGdQ1HDKc8urNPAtIMXupazYZoPrlcD1iTSya3 9X9R4mIwajwibszVXazEcPqMR/ukYbdryIFq9C3XatlwBLclb2CeDSJJmWSKm4gbT+LM Gc6Y/aBgiyKWZPAQ38YYYGMuz30V6vJi3/LzsHMaBYH2EvJDe6f7B6X6+qkdQKqouwhf 0ZLQ== X-Gm-Message-State: AOAM533Xz70xOmKx541vAhCx6VcXhpDBaY9Kkjgj/TSG8RKPRFba46wq RllgfTi3phyFgRzl8Kzq/qM= X-Google-Smtp-Source: ABdhPJxAPI/0Ac3xxOCN4zvAfkmbcnL5mU1jLjyIiq9aO2HXzi8cW2Uw5SZniELgmxOPso9AYka+6A== X-Received: by 2002:a17:902:21:b029:d2:564a:5dc6 with SMTP id 30-20020a1709020021b02900d2564a5dc6mr12808284pla.14.1602260230641; Fri, 09 Oct 2020 09:17:10 -0700 (PDT) Received: from localhost.localdomain ([49.207.205.113]) by smtp.gmail.com with ESMTPSA id s6sm9367662pfd.157.2020.10.09.09.17.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 09 Oct 2020 09:17:09 -0700 (PDT) From: Anant Thazhemadam Cc: linux-kernel-mentees@lists.linuxfoundation.org, Anant Thazhemadam , syzbot+009f546aa1370056b1c2@syzkaller.appspotmail.com, Ian Abbott , H Hartley Sweeten , Greg Kroah-Hartman , devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org Subject: [PATCH] staging: comedi: check validity of wMaxPacketSize of usb endpoints found Date: Fri, 9 Oct 2020 21:46:44 +0530 Message-Id: <20201009161646.286286-1-anant.thazhemadam@gmail.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit To: unlisted-recipients:; (no To-header on input) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org While finding usb endpoints in vmk80xx_find_usb_endpoints(), check if wMaxPacketSize = 0 for the endpoints found. Some devices have isochronous endpoints that have wMaxPacketSize = 0 (as required by the USB-2 spec). However, since this doesn't apply here, wMaxPacketSize = 0 can be considered to be invalid. Reported-by: syzbot+009f546aa1370056b1c2@syzkaller.appspotmail.com Tested-by: syzbot+009f546aa1370056b1c2@syzkaller.appspotmail.com Signed-off-by: Anant Thazhemadam --- The error (as detected by syzbot) is generated in vmk80xx_write_packet() (which is called in vmk80xx_reset_device()) when it tries to assign devpriv->usb_tx_buf[0] = cmd. This NULL pointer dereference issue arises because size = usb_endpoint_maxp(devpriv->ep_tx) = 0. This can be traced back to vmk80xx_find_usb_endpoints(), where the usb endpoints are found, and assigned accordingly. (For some more insight, in vmk80xx_find_usb_endpoints(), if one of intf->cur_altsetting->iface_desc->endpoints' desc value = 0, and consequently this endpoint is assigned to devpriv->ep_tx, this issue gets triggered.) Checking if the wMaxPacketSize of an endpoint is invalid and returning an error value accordingly, seems to fix the error. We could also alternatively perform this checking (if the size is 0 or not) in vmk80xx_reset_device() itself, but it only seemed like covering up the issue at that place, rather than fixing it, so I wasn't sure that was any better. However, if I'm not wrong, this might end up causing the probe to fail, and I'm not sure if that's the right thing to do in cases like this, and if it isn't I'd like some input on what exactly is the required course of action in cases like this. drivers/staging/comedi/drivers/vmk80xx.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/staging/comedi/drivers/vmk80xx.c b/drivers/staging/comedi/drivers/vmk80xx.c index 65dc6c51037e..cb0a965d3c37 100644 --- a/drivers/staging/comedi/drivers/vmk80xx.c +++ b/drivers/staging/comedi/drivers/vmk80xx.c @@ -667,6 +667,9 @@ static int vmk80xx_find_usb_endpoints(struct comedi_device *dev) if (!devpriv->ep_rx || !devpriv->ep_tx) return -ENODEV; + if(!usb_endpoint_maxp(devpriv->ep_rx) || !usb_endpoint_maxp(devpriv->ep_tx)) + return -EINVAL; + return 0; } -- 2.25.1