Commit c9a4cb20 authored Sep 10, 2018 by Alan Stern Committed by Greg Kroah-Hartman Sep 20, 2018

USB: handle NULL config in usb_find_alt_setting()



usb_find_alt_setting() takes a pointer to a struct usb_host_config as
an argument; it searches for an interface with specified interface and
alternate setting numbers in that config.  However, it crashes if the
usb_host_config pointer argument is NULL.

Since this is a general-purpose routine, available for use in many
places, we want to to be more robust.  This patch makes it return NULL
whenever the config argument is NULL.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by:  <syzbot+19c3aaef85a89d451eac@syzkaller.appspotmail.com>
CC: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent bd729f9d

drivers/usb/core/usb.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -228,6 +228,8 @@ struct usb_host_interface *usb_find_alt_setting(
		struct usb_interface_cache *intf_cache = NULL;
		int i;

		if (!config)
		return NULL;
		for (i = 0; i < config->desc.bNumInterfaces; i++) {
		if (config->intf_cache[i]->altsetting[0].desc.bInterfaceNumber
		== iface_num) {

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