From 4afcb8886800131f8dd58d82754ee0c508303d46 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Wed, 28 Sep 2022 22:07:15 +0200 Subject: wifi: mac80211: fix MBSSID parsing use-after-free commit ff05d4b45dd89b922578dac497dcabf57cf771c6 upstream. When we parse a multi-BSSID element, we might point some element pointers into the allocated nontransmitted_profile. However, we free this before returning, causing UAF when the relevant pointers in the parsed elements are accessed. Fix this by not allocating the scratch buffer separately but as part of the returned structure instead, that way, there are no lifetime issues with it. The scratch buffer introduction as part of the returned data here is taken from MLO feature work done by Ilan. This fixes CVE-2022-42719. Fixes: 5023b14cf4df ("mac80211: support profile split between elements") Co-developed-by: Ilan Peer Signed-off-by: Ilan Peer Reviewed-by: Kees Cook Signed-off-by: Johannes Berg Signed-off-by: Greg Kroah-Hartman --- net/mac80211/ieee80211_i.h | 8 ++++++++ net/mac80211/util.c | 30 +++++++++++++++--------------- 2 files changed, 23 insertions(+), 15 deletions(-) diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h index e192e1ec0261..9583643b7033 100644 --- a/net/mac80211/ieee80211_i.h +++ b/net/mac80211/ieee80211_i.h @@ -1704,6 +1704,14 @@ struct ieee802_11_elems { /* whether a parse error occurred while retrieving these elements */ bool parse_error; + + /* + * scratch buffer that can be used for various element parsing related + * tasks, e.g., element de-fragmentation etc. + */ + size_t scratch_len; + u8 *scratch_pos; + u8 scratch[]; }; static inline struct ieee80211_local *hw_to_local( diff --git a/net/mac80211/util.c b/net/mac80211/util.c index 3d097386b2b9..4fc3d545e666 100644 --- a/net/mac80211/util.c +++ b/net/mac80211/util.c @@ -1503,24 +1503,26 @@ ieee802_11_parse_elems_full(struct ieee80211_elems_parse_params *params) const struct element *non_inherit = NULL; u8 *nontransmitted_profile; int nontransmitted_profile_len = 0; + size_t scratch_len = params->len; - elems = kzalloc(sizeof(*elems), GFP_ATOMIC); + elems = kzalloc(sizeof(*elems) + scratch_len, GFP_ATOMIC); if (!elems) return NULL; elems->ie_start = params->start; elems->total_len = params->len; - - nontransmitted_profile = kmalloc(params->len, GFP_ATOMIC); - if (nontransmitted_profile) { - nontransmitted_profile_len = - ieee802_11_find_bssid_profile(params->start, params->len, - elems, params->bss, - nontransmitted_profile); - non_inherit = - cfg80211_find_ext_elem(WLAN_EID_EXT_NON_INHERITANCE, - nontransmitted_profile, - nontransmitted_profile_len); - } + elems->scratch_len = scratch_len; + elems->scratch_pos = elems->scratch; + + nontransmitted_profile = elems->scratch_pos; + nontransmitted_profile_len = + ieee802_11_find_bssid_profile(params->start, params->len, + elems, params->bss, + nontransmitted_profile); + elems->scratch_pos += nontransmitted_profile_len; + elems->scratch_len -= nontransmitted_profile_len; + non_inherit = cfg80211_find_ext_elem(WLAN_EID_EXT_NON_INHERITANCE, + nontransmitted_profile, + nontransmitted_profile_len); elems->crc = _ieee802_11_parse_elems_full(params, elems, non_inherit); @@ -1554,8 +1556,6 @@ ieee802_11_parse_elems_full(struct ieee80211_elems_parse_params *params) offsetofend(struct ieee80211_bssid_index, dtim_count)) elems->dtim_count = elems->bssid_index->dtim_count; - kfree(nontransmitted_profile); - return elems; } -- cgit v1.2.3