CVE-2022-48816: NULL Pointer Dereference

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

SUNRPC: lock against ->sock changing during sysfs read

->sock can be set to NULL asynchronously unless ->recv_mutex is held. So it is important to hold that mutex. Otherwise a sysfs read can trigger an oops. Commit 17f09d3f619a ("SUNRPC: Check if the xprt is connected before handling sysfs reads") appears to attempt to fix this problem, but it only narrows the race window.