From c69b8186945c10d245586e9f9703486e9574170c Mon Sep 17 00:00:00 2001 From: Andrzej Pietrasiewicz Date: Tue, 3 Mar 2015 10:52:07 +0100 Subject: [PATCH] usb: gadget: printer: eliminate random pointer dereference struct printer_dev contains 3 list heads: tx_reqs, rx_reqs and rx_buffers. There is just one instance of this structure in the driver and it is file static, and as such initialized with all zeros. If device_create() or cdev_add() fails then "goto fail" branch is taken, which results in printer_cfg_unbind() call. The latter checks if tx_reqs, rx_reqs and rx_buffers lists are empty. The check for emptiness is in fact a check whether the "next" member of struct list_head points to the head of the list. But the heads of the lists in question have not been initialized yet and, as mentioned above, contain all zeros, so list_empty() returns false and respective "while" loop body starts executing. Here, container_of() just subtracts the offset of a struct usb_request member from an address of this same member, which results in a value somewhere near 0 or 0xfff...ff. And the argument to list_del() dereferences such a pointer which causes a disaster. This patch moves respective INIT_LIST_HEAD() invocations to a point before "goto fail" branch can be taken. Signed-off-by: Andrzej Pietrasiewicz Signed-off-by: Felipe Balbi --- Reading git-format-patch failed