wifi: mac80211: fix use-after-free in chanctx code

stable inclusion
from stable-v5.10.121
commit 6118bbdf69f4718b02d26bbcf2e497eb66004331
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5L6CQ

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6118bbdf69f4718b02d26bbcf2e497eb66004331

--------------------------------

commit 2965c4cd upstream.

In ieee80211_vif_use_reserved_context(), when we have an
old context and the new context's replace_state is set to
IEEE80211_CHANCTX_REPLACE_NONE, we free the old context
in ieee80211_vif_use_reserved_reassign(). Therefore, we
cannot check the old_ctx anymore, so we should set it to
NULL after this point.

However, since the new_ctx replace state is clearly not
IEEE80211_CHANCTX_REPLACES_OTHER, we're not going to do
anything else in this function and can just return to
avoid accessing the freed old_ctx.

Cc: stable@vger.kernel.org
Fixes: 5bcae31d ("mac80211: implement multi-vif in-place reservations")
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NKalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220601091926.df419d91b165.I17a9b3894ff0b8323ce2afdb153b101124c821e5@changeidSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>

net/mac80211/chan.c

@@ -1652,12 +1652,9 @@ int ieee80211_vif_use_reserved_context(struct ieee80211_sub_if_data *sdata)
 
 	if (new_ctx->replace_state == IEEE80211_CHANCTX_REPLACE_NONE) {
 		if (old_ctx)
-			err = ieee80211_vif_use_reserved_reassign(sdata);
-		else
-			err = ieee80211_vif_use_reserved_assign(sdata);
+			return ieee80211_vif_use_reserved_reassign(sdata);
 
-		if (err)
-			return err;
+		return ieee80211_vif_use_reserved_assign(sdata);
 	}
 
 	/*