patch "USB: handle NULL config in usb_find_alt_setting()" added to usb-linus

patch "USB: handle NULL config in usb_find_alt_setting()" added to usb-linus

[gregkh]

This is a note to let you know that I've just added the patch titled

    USB: handle NULL config in usb_find_alt_setting()

to my usb git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


>From c9a4cb204e9eb7fa7dfbe3f7d3a674fa530aa193 Mon Sep 17 00:00:00 2001
From: Alan Stern <stern@rowland.harvard.edu>
Date: Mon, 10 Sep 2018 14:00:53 -0400
Subject: 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>
---
 drivers/usb/core/usb.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index 623be3174fb3..79d8bd7a612e 100644
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -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) {
-- 
2.19.0