CVE-2026-98709: wifi: mac80211: count only matching reservations in reserved switch

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

wifi: mac80211: count only matching reservations in reserved switch

ieee80211vifusereservedswitch() validates a replacement by counting assigned links on ctx->replacectx and treating reservations too broadly. A link can still be assigned to the old channel context while holding a reservation that belongs to a different replacement operation.

That can make the current replacement appear complete too early. If another link finalizes first, the function can free the WILLBEREPLACED chanctx while the unmatched link and driver still use it, leading to a use-after-free in later beacon generation.

Require an in-place reservation to point at the current replacement context, and require the reserved and assigned contexts to be the matching replacement pair, before counting or moving the link.