CVE-2024-36971 net: fix __dst_negative_advice() race

In the Linux kernel, the following vulnerability has been resolved: net: fix dstnegativeadvice race dstnegativeadvice does not enforce proper RCU rules when sk-dstcache must be cleared, leading to possible UAF. RCU rules are that we must first clear sk-skdstcache, then call dstreleaseolddst. Note...