5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Zhiling Zou [ Upstream commit 3412e9a800786d1dec4a58367db1cba275e7ef11 ] An in-place replacement keeps reciprocal replace_ctx pointers between the old WILL_BE_REPLACED chanctx and the new REPLACES_OTHER chanctx. However, the early free paths only consider assigned and reserved link users when deciding whether to free the old chanctx. That lets the old chanctx be freed too early while the replacement partner still points back to it, either when the last assigned link is released or when that link successfully reassigns to another existing context. Later unreserve and switch-finalization paths can then follow a stale replace_ctx pointer. Keep a paired old chanctx alive until the replacement pair has been torn down. Apply the same check to both __ieee80211_link_release_channel() and ieee80211_link_use_reserved_reassign(). If the replacement is later abandoned, ieee80211_link_unreserve_chanctx() already tears down the pairing before freeing the old chanctx once no users remain. 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/b9b582b0db3814f641648b8886bb50f9d68f93ac.1785730815.git.zhilinz@nebusec.ai Signed-off-by: Johannes Berg [ sashal: adapted link-based chanctx handling to the older vif-based API ] Signed-off-by: Sasha Levin --- net/mac80211/chan.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/net/mac80211/chan.c b/net/mac80211/chan.c index 5639a71257e41..0d0bb18a77e79 100644 --- a/net/mac80211/chan.c +++ b/net/mac80211/chan.c @@ -846,6 +846,7 @@ void ieee80211_vif_copy_chanctx_to_vlans(struct ieee80211_sub_if_data *sdata, int ieee80211_vif_unreserve_chanctx(struct ieee80211_sub_if_data *sdata) { struct ieee80211_chanctx *ctx = sdata->reserved_chanctx; + struct ieee80211_chanctx *old_ctx = NULL; lockdep_assert_held(&sdata->local->chanctx_mtx); @@ -860,6 +861,7 @@ int ieee80211_vif_unreserve_chanctx(struct ieee80211_sub_if_data *sdata) if (WARN_ON(!ctx->replace_ctx)) return -EINVAL; + old_ctx = ctx->replace_ctx; WARN_ON(ctx->replace_ctx->replace_state != IEEE80211_CHANCTX_WILL_BE_REPLACED); WARN_ON(ctx->replace_ctx->replace_ctx != ctx); @@ -870,6 +872,10 @@ int ieee80211_vif_unreserve_chanctx(struct ieee80211_sub_if_data *sdata) list_del_rcu(&ctx->list); kfree_rcu(ctx, rcu_head); + + if (ieee80211_chanctx_refcount(sdata->local, + old_ctx) == 0) + ieee80211_free_chanctx(sdata->local, old_ctx); } else { ieee80211_free_chanctx(sdata->local, ctx); } @@ -1078,7 +1084,9 @@ ieee80211_vif_use_reserved_reassign(struct ieee80211_sub_if_data *sdata) ieee80211_check_fast_xmit_iface(sdata); - if (ieee80211_chanctx_refcount(local, old_ctx) == 0) + if (ieee80211_chanctx_refcount(local, old_ctx) == 0 && + !(old_ctx->replace_state == IEEE80211_CHANCTX_WILL_BE_REPLACED && + old_ctx->replace_ctx)) ieee80211_free_chanctx(local, old_ctx); if (sdata->vif.bss_conf.chandef.width != sdata->reserved_chandef.width) @@ -1555,7 +1563,9 @@ static void __ieee80211_vif_release_channel(struct ieee80211_sub_if_data *sdata) } ieee80211_assign_vif_chanctx(sdata, NULL); - if (ieee80211_chanctx_refcount(local, ctx) == 0) + if (ieee80211_chanctx_refcount(local, ctx) == 0 && + !(ctx->replace_state == IEEE80211_CHANCTX_WILL_BE_REPLACED && + ctx->replace_ctx)) ieee80211_free_chanctx(local, ctx); sdata->radar_required = false; -- 2.53.0