linux-usb.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: "M. Vefa Bicakci" <m.v.b@runbox.com>
To: linux-usb@vger.kernel.org
Cc: "M. Vefa Bicakci" <m.v.b@runbox.com>,
	stable@vger.kernel.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Alan Stern <stern@rowland.harvard.edu>,
	Bastien Nocera <hadess@hadess.net>,
	Andrey Konovalov <andreyknvl@google.com>,
	syzkaller@googlegroups.com
Subject: [PATCH 2/3] usbcore/driver: Fix incorrect downcast
Date: Thu, 17 Sep 2020 17:41:50 +0300	[thread overview]
Message-ID: <20200917144151.355848-2-m.v.b@runbox.com> (raw)
In-Reply-To: <20200917144151.355848-1-m.v.b@runbox.com>

This commit resolves a minor bug in the selection/discovery of more
specific USB device drivers for devices that are currently bound to
generic USB device drivers.

The bug is related to the way a candidate USB device driver is
compared against the generic USB device driver. The code in
is_dev_usb_generic_driver() assumes that the device driver in question
is a USB device driver by calling to_usb_device_driver(dev->driver)
to downcast; however I have observed that this assumption is not always
true, through code instrumentation.

Given that USB device drivers are bound to struct device instances with
of the type &usb_device_type, this commit checks the return value of
is_usb_device() before the call to is_dev_usb_generic_driver(), and
therefore ensures that incorrect type downcasts do not occur. The use
of is_usb_device() was suggested by Bastien Nocera.

This bug was found while investigating Andrey Konovalov's report
indicating USB/IP subsystem's misbehaviour with the generic USB device
driver matching code.

Fixes: d5643d2249 ("USB: Fix device driver race")
Link: https://lore.kernel.org/linux-usb/CAAeHK+zOrHnxjRFs=OE8T=O9208B9HP_oo8RZpyVOZ9AJ54pAA@mail.gmail.com/
Cc: <stable@vger.kernel.org> # 5.8
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Bastien Nocera <hadess@hadess.net>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: <syzkaller@googlegroups.com>
Signed-off-by: M. Vefa Bicakci <m.v.b@runbox.com>
---
 drivers/usb/core/driver.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index 950044a6e77f..ba7acd6e7cc4 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -919,7 +919,7 @@ static int __usb_bus_reprobe_drivers(struct device *dev, void *data)
 	struct usb_device *udev;
 	int ret;
 
-	if (!is_dev_usb_generic_driver(dev))
+	if (!is_usb_device(dev) || !is_dev_usb_generic_driver(dev))
 		return 0;
 
 	udev = to_usb_device(dev);
-- 
2.26.2


  reply	other threads:[~2020-09-17 14:44 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-16 13:33 USB driver ID matching broken Andrey Konovalov
2020-09-16 14:15 ` Greg Kroah-Hartman
2020-09-16 14:39   ` Bastien Nocera
2020-09-16 15:58     ` M. Vefa Bicakci
2020-09-17  9:59       ` [PATCH 1/2] usbcore/driver: Fix specific driver selection M. Vefa Bicakci
2020-09-17  9:59         ` [PATCH 2/2] usbip: Make the driver's match function specific M. Vefa Bicakci
2020-09-17 10:23         ` [PATCH 1/2] usbcore/driver: Fix specific driver selection Bastien Nocera
2020-09-17 10:39           ` M. Vefa Bicakci
2020-09-17 10:49             ` Bastien Nocera
2020-09-17 14:41               ` [PATCH 1/3] " M. Vefa Bicakci
2020-09-17 14:41                 ` M. Vefa Bicakci [this message]
2020-09-17 15:01                   ` [PATCH 2/3] usbcore/driver: Fix incorrect downcast Alan Stern
2020-09-18  9:26                     ` M. Vefa Bicakci
2020-09-17 14:41                 ` [PATCH 3/3] usbip: Make the driver's match function specific M. Vefa Bicakci
2020-09-17 15:21                   ` Shuah Khan
2020-09-18  9:26                     ` M. Vefa Bicakci
2020-09-18 14:31                       ` M. Vefa Bicakci
2020-09-18 15:49                         ` Shuah Khan
2020-09-19 13:54                           ` M. Vefa Bicakci
2020-09-21 17:03                             ` M. Vefa Bicakci
2020-09-18 14:31                 ` [PATCH 1/3] usbcore/driver: Fix specific driver selection M. Vefa Bicakci
2020-09-18 14:52                   ` Alan Stern
2020-09-19 13:52                     ` M. Vefa Bicakci

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200917144151.355848-2-m.v.b@runbox.com \
    --to=m.v.b@runbox.com \
    --cc=andreyknvl@google.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=hadess@hadess.net \
    --cc=linux-usb@vger.kernel.org \
    --cc=stable@vger.kernel.org \
    --cc=stern@rowland.harvard.edu \
    --cc=syzkaller@googlegroups.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).