CVE-2021-47528

In the Linux kernel, the following vulnerability has been resolved: usb:
cdnsp: Fix a NULL pointer dereference in cdnsp_endpoint_init() In
cdnsp_endpoint_init(), cdnsp_ring_alloc() is assigned to pep->ring and
there is a dereference of it in cdnsp_endpoint_init(), which could lead to
a NULL pointer dereference on failure of cdnsp_ring_alloc(). Fix this bug
by adding a check of pep->ring. This bug was found by a static analyzer.
The analysis employs differential checking to identify inconsistent
security operations (e.g., checks or kfrees) between two code paths and
confirms that the inconsistent operations are not recovered in the current
function or the callers, so they constitute bugs. Note that, as a bug found
by static analysis, it can be a false positive or hard to trigger. Multiple
researchers have cross-reviewed the bug. Builds with
CONFIG_USB_CDNSP_GADGET=y show no new warnings, and our static analyzer no
longer warns about this code.