From 295adaf455bec573fd730b887a072d07861b03c0 Mon Sep 17 00:00:00 2001 From: Miri Korenblit Date: Thu, 2 Jan 2025 16:20:09 +0200 Subject: [PATCH] wifi: mac80211: avoid double free in auth/assoc timeout In case of authentication/association timeout (as detected in ieee80211_iface_work->ieee80211_sta_work), ieee80211_destroy_auth_data is called. At the beginning of it, the pointer to ifmgd::auth_data memory is copied to a local variable. If iface_work is queued again during the execution of the current one, and then the driver is flushing the wiphy_works (for its needs), ieee80211_destroy_auth_data will run again and free auth_data. Then when the execution of the original worker continues, the previously copied pointer will be freed, causing a kernel bug: kernel BUG at mm/slub.c:553! (double free) Same for association timeout (just with ieee80211_destroy_assoc_data and ifmgd::assoc_data) Fix this by NULLifying auth/assoc data right after we copied the pointer to it. That way, even in the scenario above, the code will not handle the same timeout twice. Signed-off-by: Miri Korenblit Reviewed-by: Johannes Berg Link: https://patch.msgid.link/20250102161730.0c3f7f781096.I2b458fb53291b06717077a815755288a81274756@changeid Signed-off-by: Johannes Berg --- net/mac80211/mlme.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c index 9bc0db308a96..0d3f64eb573e 100644 --- a/net/mac80211/mlme.c +++ b/net/mac80211/mlme.c @@ -4402,6 +4402,8 @@ static void ieee80211_destroy_auth_data(struct ieee80211_sub_if_data *sdata, lockdep_assert_wiphy(sdata->local->hw.wiphy); + sdata->u.mgd.auth_data = NULL; + if (!assoc) { /* * we are not authenticated yet, the only timer that could be @@ -4423,7 +4425,6 @@ static void ieee80211_destroy_auth_data(struct ieee80211_sub_if_data *sdata, cfg80211_put_bss(sdata->local->hw.wiphy, auth_data->bss); kfree(auth_data); - sdata->u.mgd.auth_data = NULL; } enum assoc_status { @@ -4440,6 +4441,8 @@ static void ieee80211_destroy_assoc_data(struct ieee80211_sub_if_data *sdata, lockdep_assert_wiphy(sdata->local->hw.wiphy); + sdata->u.mgd.assoc_data = NULL; + if (status != ASSOC_SUCCESS) { /* * we are not associated yet, the only timer that could be @@ -4478,7 +4481,6 @@ static void ieee80211_destroy_assoc_data(struct ieee80211_sub_if_data *sdata, } kfree(assoc_data); - sdata->u.mgd.assoc_data = NULL; } static void ieee80211_auth_challenge(struct ieee80211_sub_if_data *sdata, -- 2.50.1