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=-17.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 90D4DC636C8 for ; Tue, 20 Jul 2021 12:13:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 706686113B for ; Tue, 20 Jul 2021 12:13:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237024AbhGTLcn (ORCPT ); Tue, 20 Jul 2021 07:32:43 -0400 Received: from lb3-smtp-cloud9.xs4all.net ([194.109.24.30]:34915 "EHLO lb3-smtp-cloud9.xs4all.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231707AbhGTLck (ORCPT ); Tue, 20 Jul 2021 07:32:40 -0400 Received: from cust-b5b5937f ([IPv6:fc0c:c16d:66b8:757f:c639:739b:9d66:799d]) by smtp-cloud9.xs4all.net with ESMTPA id 5ocbmt71dhqx95occmvjYR; Tue, 20 Jul 2021 14:13:15 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=xs4all.nl; s=s2; t=1626783195; bh=8LNbX59qTEjPV5haDNG1ReO6rc37pgbdjgLqdJPr36U=; h=Subject:To:From:Message-ID:Date:MIME-Version:Content-Type:From: Subject; b=S0veEs2dKYjQaSSRFOALKiR+7lSNBgoqCq77lF1PJAG4i4oAt1Z/xlaJoY7kMgb9n uaA8gFhgRzmooB82CwXWIuydMdheJ0wYuSaXhzi3MMKt1uq5UMDQE2f8O/SwtoiAMi IJWMCkAgYgfhrEuBp8AFb4XWoQN5dMpXnZ9hmyKuGKi4K8mrfRKzg4Po7mttYNm0nn gmpxqtKnT7FEGshUug9IdbjdOJWlnWhSNhNvDGcwvjL1pGqFgdRzL4p4mMYYwwKwI0 ACsOC1UB9DKOgQz9FeYvcjw9ekhMPaAjoWp/bjZ48jZEuOOli6PYYgu7qWycWIN3c5 ubfyYgwwQUmPQ== Subject: Re: [PATCH] media: em28xx: fix corrupted list To: Pavel Skripkin , mchehab@kernel.org Cc: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+a6969ef522a36d3344c9@syzkaller.appspotmail.com References: <20210706145025.25776-1-paskripkin@gmail.com> From: Hans Verkuil Message-ID: Date: Tue, 20 Jul 2021 14:13:13 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210706145025.25776-1-paskripkin@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-CMAE-Envelope: MS4xfKCqy+MZNsZBoM/nl8NEJHCiuF065/vJ60zpyfe9tpSxK5FXvkTFXuiI4V4Bwl15LRszCQ+7r5seEfaTbjO930qqFLwN/fLXjsILEhMegbMLosfWAX3i BS66QxpEhQmxfAXf4ItFjzututqkihdnS8HpzFJA8ARcV3fP8iYKZT5FsmeUt6PI1Q7sUgaq1eJIR6sP8wWcyYJDT3hd2bAQjIOlRaZRetcngLPtjF/BfExc HyMIrnh8Uca0T81bL2Mg8RRZGBnUH1f745kOxzICdRJ0HkGfl1PSIjtZOY/iDPx+RRkyAlGBQyOjRV5jBQJbxY+twJAPC8DKWRUFRLsk2/jpfQ9udz4kZQPA Wo1XV8gChU3MpUh8b7eXR3ETOoZX4sX/PVjdTlnleJFNzdM9yI8kVdS16dw7kHWcLXu/Oj1nYTNgtYB1WFRcrF1FFwkO3QsDqzO302a0yv8FjF7Lv6ZTVq7r o1QOieYqQf7JgLHz Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/07/2021 16:50, Pavel Skripkin wrote: > Syzbot reported corrupted list in em28xx driver. The problem was in > non-reinitialized lists on disconnect. Since all 2 lists are global > variables and driver can be connected and disconnected many times we > should call INIT_LIST_HEAD() in .disconnect method to prevent corrupted > list entries. > > Fixes: 1a23f81b7dc3 ("V4L/DVB (9979): em28xx: move usb probe code to a proper place") > Reported-by: syzbot+a6969ef522a36d3344c9@syzkaller.appspotmail.com > Signed-off-by: Pavel Skripkin > --- > drivers/media/usb/em28xx/em28xx-cards.c | 2 ++ > drivers/media/usb/em28xx/em28xx-core.c | 6 ++++++ > drivers/media/usb/em28xx/em28xx.h | 1 + > 3 files changed, 9 insertions(+) > > diff --git a/drivers/media/usb/em28xx/em28xx-cards.c b/drivers/media/usb/em28xx/em28xx-cards.c > index ba9292e2a587..8b1ff79c37a0 100644 > --- a/drivers/media/usb/em28xx/em28xx-cards.c > +++ b/drivers/media/usb/em28xx/em28xx-cards.c > @@ -4148,6 +4148,8 @@ static void em28xx_usb_disconnect(struct usb_interface *intf) > dev->dev_next = NULL; > } > kref_put(&dev->ref, em28xx_free_device); > + > + em28xx_reset_lists(); > } > > static int em28xx_usb_suspend(struct usb_interface *intf, > diff --git a/drivers/media/usb/em28xx/em28xx-core.c b/drivers/media/usb/em28xx/em28xx-core.c > index 584fa400cd7d..03970ed00dba 100644 > --- a/drivers/media/usb/em28xx/em28xx-core.c > +++ b/drivers/media/usb/em28xx/em28xx-core.c > @@ -1131,6 +1131,12 @@ void em28xx_init_extension(struct em28xx *dev) > mutex_unlock(&em28xx_devlist_mutex); > } > > +void em28xx_reset_lists(void) > +{ > + INIT_LIST_HEAD(&em28xx_devlist); > + INIT_LIST_HEAD(&em28xx_extension_devlist); This needs a mutex_lock(&em28xx_devlist_mutex); But actually, I don't think this is right: if there are multiple em28xx devices, then I think if you disconnect one, then the other is - with this code - also removed from the list. Can you give a link to the actual syzbot bug? I'm not at all sure you are fixing the right thing here. Regards, Hans > +} > + > void em28xx_close_extension(struct em28xx *dev) > { > const struct em28xx_ops *ops = NULL; > diff --git a/drivers/media/usb/em28xx/em28xx.h b/drivers/media/usb/em28xx/em28xx.h > index ab167cd1f400..73caaaa398d3 100644 > --- a/drivers/media/usb/em28xx/em28xx.h > +++ b/drivers/media/usb/em28xx/em28xx.h > @@ -835,6 +835,7 @@ void em28xx_stop_urbs(struct em28xx *dev); > int em28xx_set_mode(struct em28xx *dev, enum em28xx_mode set_mode); > int em28xx_gpio_set(struct em28xx *dev, const struct em28xx_reg_seq *gpio); > int em28xx_register_extension(struct em28xx_ops *dev); > +void em28xx_reset_lists(void); > void em28xx_unregister_extension(struct em28xx_ops *dev); > void em28xx_init_extension(struct em28xx *dev); > void em28xx_close_extension(struct em28xx *dev); >