From 437f3727b4fd715266c296435c116288f82666fd Mon Sep 17 00:00:00 2001 From: Zhiling Zou Date: Mon, 3 Aug 2026 11:28:22 +0800 Subject: [PATCH] wifi: mac80211: count only matching reservations in reserved switch ieee80211_vif_use_reserved_switch() validates a replacement by counting assigned links on ctx->replace_ctx 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 WILL_BE_REPLACED 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. Fixes: 5bcae31d9cb1 ("mac80211: implement multi-vif in-place reservations") Cc: stable@vger.kernel.org Reported-by: Vega Signed-off-by: Zhiling Zou Link: https://patch.msgid.link/4b6c4b8648ab1920c38a40be32c0b1a2797b4ac6.1785726007.git.zhilinz@nebusec.ai Signed-off-by: Johannes Berg --- net/mac80211/chan.c | 30 +++++++++++++++++++++++------- 1 file changed, 23 insertions(+), 7 deletions(-) diff --git a/net/mac80211/chan.c b/net/mac80211/chan.c index 75bb204ad743..17b935448f13 100644 --- a/net/mac80211/chan.c +++ b/net/mac80211/chan.c @@ -1772,7 +1772,8 @@ out: } static bool -ieee80211_link_has_in_place_reservation(struct ieee80211_link_data *link) +ieee80211_link_has_in_place_reservation(struct ieee80211_link_data *link, + struct ieee80211_chanctx *ctx) { struct ieee80211_sub_if_data *sdata = link->sdata; struct ieee80211_chanctx *old_ctx, *new_ctx; @@ -1782,6 +1783,9 @@ ieee80211_link_has_in_place_reservation(struct ieee80211_link_data *link) new_ctx = link->reserved_chanctx; old_ctx = ieee80211_link_get_chanctx(link); + if (new_ctx != ctx) + return false; + if (!old_ctx) return false; @@ -1794,6 +1798,12 @@ ieee80211_link_has_in_place_reservation(struct ieee80211_link_data *link) if (new_ctx->replace_state != IEEE80211_CHANCTX_REPLACES_OTHER) return false; + if (new_ctx->replace_ctx != old_ctx) + return false; + + if (old_ctx->replace_ctx != new_ctx) + return false; + return true; } @@ -1823,7 +1833,8 @@ static int ieee80211_chsw_switch_vifs(struct ieee80211_local *local, } for_each_chanctx_user_reserved(local, ctx, &iter) { - if (!ieee80211_link_has_in_place_reservation(iter.link)) + if (!ieee80211_link_has_in_place_reservation(iter.link, + ctx)) continue; old_ctx = ieee80211_link_get_chanctx(iter.link); @@ -1925,7 +1936,9 @@ static int ieee80211_vif_use_reserved_switch(struct ieee80211_local *local) for_each_chanctx_user_assigned(local, ctx->replace_ctx, &iter) { n_assigned++; - if (iter.link && iter.link->reserved_chanctx) { + if (iter.link && + ieee80211_link_has_in_place_reservation(iter.link, + ctx)) { n_reserved++; if (iter.link->reserved_ready) n_ready++; @@ -1950,7 +1963,8 @@ static int ieee80211_vif_use_reserved_switch(struct ieee80211_local *local) use_reserved: ctx->conf.radar_enabled = false; for_each_chanctx_user_reserved(local, ctx, &iter) { - if (ieee80211_link_has_in_place_reservation(iter.link) && + if (ieee80211_link_has_in_place_reservation(iter.link, + ctx) && !iter.link->reserved_ready) return -EAGAIN; @@ -1991,7 +2005,8 @@ use_reserved: } for_each_chanctx_user_reserved(local, ctx, &iter) { - if (!ieee80211_link_has_in_place_reservation(iter.link)) + if (!ieee80211_link_has_in_place_reservation(iter.link, + ctx)) continue; ieee80211_chan_bw_change(local, @@ -2040,7 +2055,7 @@ use_reserved: struct ieee80211_bss_conf *link_conf = link->conf; u64 changed = 0; - if (!ieee80211_link_has_in_place_reservation(link)) + if (!ieee80211_link_has_in_place_reservation(link, ctx)) continue; rcu_assign_pointer(link_conf->chanctx_conf, @@ -2091,7 +2106,8 @@ use_reserved: for_each_chanctx_user_reserved(local, ctx, &iter) { struct ieee80211_link_data *link = iter.link; - if (WARN_ON(ieee80211_link_has_in_place_reservation(link))) + if (WARN_ON(ieee80211_link_has_in_place_reservation(link, + ctx))) continue; if (!link->reserved_ready)