Describe CVE-2021-47251.
What is CVE-2021-47251?
In the Linux kernel, the following vulnerability has been resolved:

mac80211: fix skb length check in ieee80211_scan_rx()

Replace hard-coded compile-time constants for header length check
with dynamic determination based on the frame type. Otherwise, we
hit a validation WARN_ON in cfg80211 later.

[style fixes, reword commit message].