[PATCH] USB: usbip: fix null-ptr-deref in status_show_vhci()

[Qasim Ijaz <qasdev00@gmail.com>]

If usb_add_hcd() fails in vhci_hcd_probe() (i.e., a probe failure),
the error path calls usb_remove_hcd() and also sets 
pdev->dev.driver_data to NULL.

Consequently, any subsequent call to platform_get_drvdata(pdev) 
(which returns pdev->dev.driver_data) may yield NULL, causing a 
crash if that pointer is dereferenced.

Fix this by adding a sanity check to ensure "hcd" is non-NULL
before proceeding with further operations.

Reported-by: syzbot <syzbot+83976e47ec1ef91e66f1@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=83976e47ec1ef91e66f1
Tested-by: syzbot <syzbot+83976e47ec1ef91e66f1@syzkaller.appspotmail.com>
Fixes: 03cd00d538a6 ("usbip: vhci-hcd: Set the vhci structure up to work")
Signed-off-by: Qasim Ijaz <qasdev00@gmail.com>
---
 drivers/usb/usbip/vhci_sysfs.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/usb/usbip/vhci_sysfs.c b/drivers/usb/usbip/vhci_sysfs.c
index d5865460e82d..a5e6c3c4af06 100644
--- a/drivers/usb/usbip/vhci_sysfs.c
+++ b/drivers/usb/usbip/vhci_sysfs.c
@@ -76,6 +76,10 @@ static ssize_t status_show_vhci(int pdev_nr, char *out)
 	}
 
 	hcd = platform_get_drvdata(pdev);
+
+	if (!hcd)
+		return 0;
+
 	vhci_hcd = hcd_to_vhci_hcd(hcd);
 	vhci = vhci_hcd->vhci;
 
-- 
2.39.5