can: etas_es58x: fix potential NULL pointer dereference on udev->serial

can: etas_es58x: fix potential NULL pointer dereference on udev->serial

commit a1ad2109ce41c9e3912dadd07ad8a9c640064ffb upstream.

The driver assumed that es58x_dev->udev->serial could never be NULL.
While this is true on commercially available devices, an attacker
could spoof the device identity providing a NULL USB serial number.
That would trigger a NULL pointer dereference.

Add a check on es58x_dev->udev->serial before accessing it.

Reported-by: yan kang <kangyan91@outlook.com>
Reported-by: yue sun <samsun1006219@gmail.com>
Closes: https://lore.kernel.org/linux-can/SY8P300MB0421E0013C0EBD2AA46BA709A1F42@SY8P300MB0421.AUSP300.PROD.OUTLOOK.COM/
Fixes: 9f06631c3f1f ("can: etas_es58x: export product information through devlink_ops::info_get()")
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://patch.msgid.link/20250204154859.9797-2-mailhol.vincent@wanadoo.fr
Cc: stable@vger.kernel.org
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>