From 44995e6f07028f798efd0c3c11a1efc78330f600 Mon Sep 17 00:00:00 2001
From: Douglas Anderson <dianders@chromium.org>
Date: Mon, 11 Dec 2023 07:32:41 -0800
Subject: [PATCH] usb: core: Fix crash w/ usb_choose_configuration() if no
driver
Git-commit: 44995e6f07028f798efd0c3c11a1efc78330f600
References: git-fixes
Patch-mainline: v6.8-rc1
It's possible that usb_choose_configuration() can get called when a
USB device has no driver. In this case the recent commit a87b8e3be926
("usb: core: Allow subclassed USB drivers to override
usb_choose_configuration()") can cause a crash since it dereferenced
the driver structure without checking for NULL. Let's add a check.
A USB device with no driver is an anomaly, so make
usb_choose_configuration() return immediately if there is no driver.
This was seen in the real world when usbguard got ahold of a r8152
device at the wrong time. It can also be simulated via this on a
computer with one r8152-based USB Ethernet adapter:
cd /sys/bus/usb/drivers/r8152-cfgselector
to_unbind="$(ls -d *-*)"
real_dir="$(readlink -f "${to_unbind}")"
echo "${to_unbind}" > unbind
cd "${real_dir}"
echo 0 > authorized
echo 1 > authorized
Fixes: a87b8e3be926 ("usb: core: Allow subclassed USB drivers to override usb_choose_configuration()")
Reviewed-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20231211073237.v3.1.If27eb3bf7812f91ab83810f232292f032f4203e0@changeid
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
drivers/usb/core/generic.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/core/generic.c b/drivers/usb/core/generic.c
index dcb897158228..b134bff5c3fe 100644
--- a/drivers/usb/core/generic.c
+++ b/drivers/usb/core/generic.c
@@ -59,7 +59,16 @@ int usb_choose_configuration(struct usb_device *udev)
int num_configs;
int insufficient_power = 0;
struct usb_host_config *c, *best;
- struct usb_device_driver *udriver = to_usb_device_driver(udev->dev.driver);
+ struct usb_device_driver *udriver;
+
+ /*
+ * If a USB device (not an interface) doesn't have a driver then the
+ * kernel has no business trying to select or install a configuration
+ * for it.
+ */
+ if (!udev->dev.driver)
+ return -1;
+ udriver = to_usb_device_driver(udev->dev.driver);
if (usb_device_is_owned(udev))
return 0;
--
2.43.0