CVE-2021-47248

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

udp: fix race between close() and udp_abort()

Kaustubh reported and diagnosed a panic in udpliblookup(). The root cause is udpabort() racing with close(). Both racing functions acquire the socket lock, but udp{v6}destroy_sock() release it before performing destructive actions.

We can't easily extend the socket lock scope to avoid the race, instead use the SOCKDEAD flag to prevent udpabort from doing any action when the critical race happens.

Diagnosed-and-tested-by: Kaustubh Pandey kapandey@codeaurora.org