usb: gadget: f_hid: don't call cdev_init while cdev in use

Overview

In the Linux kernel, the following vulnerability has been resolved:

usb: gadget: f_hid: don't call cdev_init while cdev in use

When calling unbind, then bind again, cdev_init reinitialized the cdev, even though there may still be references to it. That's the case when the /dev/hidg* device is still opened. This obviously unsafe behavior like oopes.

This fixes this by using cdev_alloc to put the cdev on the heap. That way, we can simply allocate a new one in hidg_bind.

Affected

• Linux >= cb382536052fcc7713988869b54a81137069e5a9 < 3aa77f5da0ecb00895411f4246d8a3e4db0343c2
• Linux >= cb382536052fcc7713988869b54a81137069e5a9 < c6c0d13db5d0f8d465eabc14bd23d2b6a7247a43
• Linux >= cb382536052fcc7713988869b54a81137069e5a9 < eb6ef6185f2054a341ec70d7e2165f5381744215
• Linux >= cb382536052fcc7713988869b54a81137069e5a9 < 5a229016ca3ac551294ec59770be9da94ec4bf63
• Linux >= cb382536052fcc7713988869b54a81137069e5a9 < 75ecc46828ec377dd5692c677168ef6d64fd7123
• Linux >= cb382536052fcc7713988869b54a81137069e5a9 < 81ebd43cc0d6d106ce7b6ccbf7b5e40ca7f5503d
• Linux 3.19

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.