2023-09-19 06:34:36

by Johannes Berg

Subject: [PATCH 1/2] wifi: mac80211: fix potential key use-after-free

From: Johannes Berg <[email protected]>

When ieee80211_key_link() is called by ieee80211_gtk_rekey_add()
but returns 0 due to KRACK protection (identical key reinstall),
ieee80211_gtk_rekey_add() will still return a pointer into the
key, in a potential use-after-free. This normally doesn't happen
since it's only called by iwlwifi in case of WoWLAN rekey offload
which has its own KRACK protection, but still better to fix, do
that by returning an error code and converting that to success on
the cfg80211 boundary only, leaving the error for bad callers of
ieee80211_gtk_rekey_add().

Reported-by: Dan Carpenter <[email protected]>
Fixes: fdf7cb4185b6 ("mac80211: accept key reinstall without changing anything")
Signed-off-by: Johannes Berg <[email protected]>
---
net/mac80211/cfg.c | 3 +++
net/mac80211/key.c | 2 +-
2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 45e7a5d9c7d9..e883c41a2163 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -566,6 +566,9 @@ static int ieee80211_add_key(struct wiphy *wiphy, struct net_device *dev,
}

err = ieee80211_key_link(key, link, sta);
+ /* KRACK protection, shouldn't happen but just silently accept key */
+ if (err == -EALREADY)
+ err = 0;

out_unlock:
mutex_unlock(&local->sta_mtx);
diff --git a/net/mac80211/key.c b/net/mac80211/key.c
index 13050dc9321f..84ba20c3e3dc 100644
--- a/net/mac80211/key.c
+++ b/net/mac80211/key.c
@@ -905,7 +905,7 @@ int ieee80211_key_link(struct ieee80211_key *key,
*/
if (ieee80211_key_identical(sdata, old_key, key)) {
ieee80211_key_free_unused(key);
- ret = 0;
+ ret = -EALREADY;
goto out;
}

--
2.41.0

2023-09-19 06:45:26

by Johannes Berg

Subject: [PATCH 2/2] wifi: mac80211: fix potential key leak

From: Johannes Berg <[email protected]>

When returning from ieee80211_key_link(), the key needs to
have been freed or successfully installed. This was missed
in a number of error paths, fix it.

Signed-off-by: Johannes Berg <[email protected]>
---
net/mac80211/key.c | 20 +++++++++++++++-----
1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/net/mac80211/key.c b/net/mac80211/key.c
index 84ba20c3e3dc..0665ff5e456e 100644
--- a/net/mac80211/key.c
+++ b/net/mac80211/key.c
@@ -802,6 +802,9 @@ static void ieee80211_key_destroy(struct ieee80211_key *key,

void ieee80211_key_free_unused(struct ieee80211_key *key)
{
+ if (!key)
+ return;
+
WARN_ON(key->sdata || key->local);
ieee80211_key_free_common(key);
}
@@ -854,7 +857,7 @@ int ieee80211_key_link(struct ieee80211_key *key,
* can cause warnings to appear.
*/
bool delay_tailroom = sdata->vif.type == NL80211_IFTYPE_STATION;
- int ret = -EOPNOTSUPP;
+ int ret;

mutex_lock(&sdata->local->key_mtx);

@@ -868,8 +871,10 @@ int ieee80211_key_link(struct ieee80211_key *key,
* the same cipher. Enforce the assumption for pairwise keys.
*/
if ((alt_key && alt_key->conf.cipher != key->conf.cipher) ||
- (old_key && old_key->conf.cipher != key->conf.cipher))
+ (old_key && old_key->conf.cipher != key->conf.cipher)) {
+ ret = -EOPNOTSUPP;
goto out;
+ }
} else if (sta) {
struct link_sta_info *link_sta = &sta->deflink;
int link_id = key->conf.link_id;
@@ -895,8 +900,10 @@ int ieee80211_key_link(struct ieee80211_key *key,

/* Non-pairwise keys must also not switch the cipher on rekey */
if (!pairwise) {
- if (old_key && old_key->conf.cipher != key->conf.cipher)
+ if (old_key && old_key->conf.cipher != key->conf.cipher) {
+ ret = -EOPNOTSUPP;
goto out;
+ }
}

/*
@@ -904,9 +911,8 @@ int ieee80211_key_link(struct ieee80211_key *key,
* new version of the key to avoid nonce reuse or replay issues.
*/
if (ieee80211_key_identical(sdata, old_key, key)) {
- ieee80211_key_free_unused(key);
ret = -EALREADY;
- goto out;
+ goto unlock;
}

key->local = sdata->local;
@@ -930,7 +936,11 @@ int ieee80211_key_link(struct ieee80211_key *key,
ieee80211_key_free(key, delay_tailroom);
}

+ key = NULL;
+
out:
+ ieee80211_key_free_unused(key);
+ unlock:
mutex_unlock(&sdata->local->key_mtx);

return ret;
--
2.41.0