KASAN reporting: general protection fault in flexcop_usb_probe

[Oliver Neukum <oneukum@suse.com>]

Reacting to this:

Title:              general protection fault in flexcop_usb_probe
Last occurred:      0 days ago
Reported:           102 days ago
Branches:           Mainline (with usb-fuzzer patches)
Dashboard link:     https://syzkaller.appspot.com/bug?id=c0203bd72037d0
7493f4b7562411e4f5f4553a8f
Original thread:    https://lkml.kernel.org/lkml/00000000000010fe260586
536e86@google.com/T/#u

This bug has a C reproducer.

No one replied to the original thread for this bug.

This looks like a bug in a media USB driver.

If you fix this bug, please add the following tag to the commit:
    Reported-by: syzbot+d93dff37e6a89431c158@syzkaller.appspotmail.com

#syz test: https://github.com/google/kasan.git 9a33b369

From 5a34ecc6c75479a9f245a867e1ce37e6e28f58f8 Mon Sep 17 00:00:00 2001
From: Oliver Neukum <oneukum@suse.com>
Date: Mon, 29 Jul 2019 16:21:11 +0200
Subject: [PATCH] b2c2-flexcop-usb: add sanity checking

The driver needs an isochronous endpoint to be present. It will
oops in its absence. Add checking for it.

Reported-by: syzbot+d93dff37e6a89431c158@syzkaller.appspotmail.com
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
 drivers/media/usb/b2c2/flexcop-usb.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/media/usb/b2c2/flexcop-usb.c b/drivers/media/usb/b2c2/flexcop-usb.c
index 1826ff825c2e..1a801dc286f8 100644
--- a/drivers/media/usb/b2c2/flexcop-usb.c
+++ b/drivers/media/usb/b2c2/flexcop-usb.c
@@ -538,6 +538,9 @@ static int flexcop_usb_probe(struct usb_interface *intf,
 	struct flexcop_device *fc = NULL;
 	int ret;
 
+	if (intf->cur_altsetting->desc.bNumEndpoints < 1)
+		return -ENODEV;
+
 	if ((fc = flexcop_device_kmalloc(sizeof(struct flexcop_usb))) == NULL) {
 		err("out of memory\n");
 		return -ENOMEM;