From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from extorris.mess.org (extorris.mess.org [92.243.27.206]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EEB4032D0FC; Thu, 13 Aug 2026 14:02:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=92.243.27.206 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786629750; cv=none; b=n/2S9pRBYoe3uWT4uJOB2vvQt5SZiV89Co2FwtVjfGhGa2uAxeJzO7V+GdOQJf0BhKFHZmj8Z2+uhcHW2XxcoyyDj4mElvmQwuGEqt0ZSBkYe+jDGMknIbEmOaoMJ7fJ6tJ5Sp6YFkvdBOuzXgGhMFKG3DUC3d0U2+6neNMEU00= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786629750; c=relaxed/simple; bh=vbKfBch/UEEFFguO+x8EG2UHHMgwwOY2dQPtAJhBb9c=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=gdo1V4Ppmf882yK9PkMcx0nbezTAJ+DjJ3TLJWYuQQt10d3QLeTQVTTtLU3MjvcZf/O4NTAxxtS6hGa48jqPjOm/9jB77GUjT5jWd4LNX3wlOfulikZpmSZBgpRs4Ca/0JiMH4ELRo/lebyyNPXOqoUL6UFK2FMpYXw7gWbdOCc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=mess.org; spf=pass smtp.mailfrom=mess.org; dkim=pass (2048-bit key) header.d=mess.org header.i=@mess.org header.b=l0LXSmRg; arc=none smtp.client-ip=92.243.27.206 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=mess.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mess.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=mess.org header.i=@mess.org header.b="l0LXSmRg" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=mess.org; s=2020; t=1786629740; bh=vbKfBch/UEEFFguO+x8EG2UHHMgwwOY2dQPtAJhBb9c=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=l0LXSmRgLt8DhA65tPanpkIl8ch92js75Txwz3aosDrkPmyPOFeFCBTcb2V9lfKxS 1jgb/OMCQxjUMY/MeSz5hSEveImHV3jADQ5b8gsAISl7CEWHbzAcy6UDVMGMnijqyX pWLyLX/og0vNPP1rxdu4DA5W4Gt6ijp3LBrPu17d7cnomVFdSb9o0iAI3gryx6gQG2 9MyyOllluZ5A39zxLFr8N468Krfh6dgj3Q5nBsniFZj7cIZa+ppdS9fmYoZ7O625V0 Udj2QECvNCnR7OD5US2qNzGn+aclpRcsEtTpxMNnWkW+YaijkhQbWaTLWwsiryt7A7 xt3ERXqZaw7VQ== Received: by extorris.mess.org (Postfix, from userid 1001) id F070641567; Thu, 13 Aug 2026 15:02:20 +0100 (BST) Date: Thu, 13 Aug 2026 15:02:20 +0100 From: Sean Young To: Rik van Riel Cc: Mauro Carvalho Chehab , Jarod Wilson , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] media: redrat3: fix UAF in probe error path leaving rc device registered Message-ID: References: <20260808232031.500f781c@fangorn> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260808232031.500f781c@fangorn> Hoi Rik, On Sat, Aug 08, 2026 at 11:20:31PM -0400, Rik van Riel wrote: > redrat3 stores its device name and phys path inside the main rr3 > structure, and the rc device's device_name and input_phys point into > rr3. When the RC device is registered, it keeps those pointers. > > KASAN: slab-use-after-free in string_nocheck lib/vsprintf.c:648 > Read of size 1 at addr ffff888051fda758 by task udevd/7464 > Call Trace: > string_nocheck lib/vsprintf.c:648 [inline] > string+0x216/0x2d0 lib/vsprintf.c:730 > vsnprintf+0x74a/0xef0 lib/vsprintf.c:2945 > vscnprintf+0x41/0x90 lib/vsprintf.c:3014 > sysfs_emit+0x10e/0x180 fs/sysfs/file.c:761 > input_dev_show_name+0x58/0x70 drivers/input/input.c:1282 > > Allocated by task 10: > redrat3_dev_probe+0x477/0x2570 drivers/media/rc/redrat3.c:1023 > Freed by task 10: > redrat3_delete drivers/media/rc/redrat3.c:466 [inline] > redrat3_dev_probe+0x1bf4/0x2570 drivers/media/rc/redrat3.c:1124 > > Syzkaller triggers this via usb probing. It probes the RedRat3 USB > interface, which calls redrat3_dev_probe() in redrat3.c. That function > allocates rr3, then builds an rc device whose name points into rr3 via > redrat3_init_rc_dev() in redrat3.c, and registers it with > rc_register_device(). > > When the detector enable fails after the RC device is registered, the > probe jumps to the led_free path. That path unregisters the LED but does > not unregister the RC device before freeing rr3 via redrat3_delete() in > redrat3.c. The RC device still holds device_name = rr3->name which is now > freed. > > Later udevd reads /sys/.../input device name via sysfs_emit() in file.c, > which calls input_dev_show_name() in input.c, which emits dev->name which > is the freed rr3->name. > > When the detector enable fails after the RC device is registered, the > error path must not leave the RC device registered. Make the probe error > path clean up the same way redrat3_dev_disconnect() does. > > This change should be safe because the RC device is fully registered at > this point and its teardown via rc_unregister_device() is protected by > the input device mutex, and rr3 is still alive during unregister so > device_name remains valid until after unregister. The URBs are killed > before rc_free, so no completion can run after rc is freed. No new lock > ordering is introduced. > > Reported-by: syzbot+302b9b575a06733ff60c@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=302b9b575a06733ff60c > Link: https://lore.kernel.org/all/6a74a76d.ec7c9571.3ac9bb.0056.GAE@google.com/ > Fixes: 2154be651b90 ("[media] redrat3: new rc-core IR transceiver device driver") > Cc: stable@vger.kernel.org > Assisted-by: Hermes:muse-spark-1.2 syzkaller > Signed-off-by: Rik van Riel The commit message is very good. Your patch is very similar to a patch I wrote earlier (which still has to be reviewed, I can't merge my own patches without review into the media-committer tree): https://lkml.org/lkml/2026/7/29/1730 I don't really have a preference for which one to merge. Sean > --- > v2: fix the Sashiko bug https://sashiko.dev/#/patchset/20260808174213.1d68336e%40fangorn > > drivers/media/rc/redrat3.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/media/rc/redrat3.c b/drivers/media/rc/redrat3.c > index 3f828a564e19..565c490b7051 100644 > --- a/drivers/media/rc/redrat3.c > +++ b/drivers/media/rc/redrat3.c > @@ -975,6 +975,7 @@ static int redrat3_dev_probe(struct usb_interface *intf, > struct device *dev = &intf->dev; > struct usb_host_interface *uhi; > struct redrat3_dev *rr3; > + struct rc_dev *rc; > struct usb_endpoint_descriptor *ep; > struct usb_endpoint_descriptor *ep_narrow = NULL; > struct usb_endpoint_descriptor *ep_wide = NULL; > @@ -1119,9 +1120,12 @@ static int redrat3_dev_probe(struct usb_interface *intf, > return 0; > > led_free: > + rc_unregister_device(rr3->rc); > led_classdev_unregister(&rr3->led); > redrat_free: > + rc = rr3->rc; > redrat3_delete(rr3, rr3->udev); > + rc_free_device(rc); > > no_endpoints: > return retval; > -- > 2.55.0 >