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authorJohannes Berg <johannes.berg@intel.com>2022-09-28 23:07:15 +0300
committerJohannes Berg <johannes.berg@intel.com>2022-10-10 10:50:23 +0300
commitff05d4b45dd89b922578dac497dcabf57cf771c6 (patch)
treeb67ee15aea80b40cc40d2d76058b744deb3b080c /net
parent8f033d2becc24aa6bfd2a5c104407963560caabc (diff)
downloadlinux-ff05d4b45dd89b922578dac497dcabf57cf771c6.tar.xz
wifi: mac80211: fix MBSSID parsing use-after-free
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 <ilan.peer@intel.com> Signed-off-by: Ilan Peer <ilan.peer@intel.com> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Diffstat (limited to 'net')
-rw-r--r--net/mac80211/ieee80211_i.h8
-rw-r--r--net/mac80211/util.c30
2 files changed, 23 insertions, 15 deletions
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 4e1d4c339f2d..a842f2e1c230 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1709,6 +1709,14 @@ 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 f61289c5fed2..99e903299143 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -1506,24 +1506,26 @@ 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);
@@ -1557,8 +1559,6 @@ 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;
}