From 12783c0b9e2c7915a50d5ec829630ff2da50472c Mon Sep 17 00:00:00 2001
From: Udipto Goswami <quic_ugoswami@quicinc.com>
Date: Wed, 10 Jan 2024 15:28:14 +0530
Subject: [PATCH] usb: core: Prevent null pointer dereference in update_port_device_state
Git-commit: 12783c0b9e2c7915a50d5ec829630ff2da50472c
Patch-mainline: v6.8-rc3
References: git-fixes CVE-2024-26716 bsc#1222359
Currently, the function update_port_device_state gets the usb_hub from
udev->parent by calling usb_hub_to_struct_hub.
However, in case the actconfig or the maxchild is 0, the usb_hub would
be NULL and upon further accessing to get port_dev would result in null
pointer dereference.
Fix this by introducing an if check after the usb_hub is populated.
Fixes: 83cb2604f641 ("usb: core: add sysfs entry for usb device state")
Cc: stable@vger.kernel.org
Signed-off-by: Udipto Goswami <quic_ugoswami@quicinc.com>
Reviewed-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/20240110095814.7626-1-quic_ugoswami@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/usb/core/hub.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index ffd7c99e24a3..48409d51ea43 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -2053,9 +2053,19 @@ static void update_port_device_state(struct usb_device *udev)
if (udev->parent) {
hub = usb_hub_to_struct_hub(udev->parent);
- port_dev = hub->ports[udev->portnum - 1];
- WRITE_ONCE(port_dev->state, udev->state);
- sysfs_notify_dirent(port_dev->state_kn);
+
+ /*
+ * The Link Layer Validation System Driver (lvstest)
+ * has a test step to unbind the hub before running the
+ * rest of the procedure. This triggers hub_disconnect
+ * which will set the hub's maxchild to 0, further
+ * resulting in usb_hub_to_struct_hub returning NULL.
+ */
+ if (hub) {
+ port_dev = hub->ports[udev->portnum - 1];
+ WRITE_ONCE(port_dev->state, udev->state);
+ sysfs_notify_dirent(port_dev->state_kn);
+ }
}
}
--
2.35.3