syzbot discovered a bug in which an OOB access was being made because
an unsuitable key_idx value was wrongly considered to be acceptable
while deleting a key in nl80211_del_key().
Since we don't know the cipher at the time of deletion, if
cfg80211_validate_key_settings() were to be called directly in
nl80211_del_key(), even valid keys would be wrongly determined invalid,
and deletion wouldn't occur correctly.
For this reason, a new function - cfg80211_valid_key_idx(), has been
created, to determine if the key_idx value provided is valid or not.
cfg80211_valid_key_idx() is directly called in 2 places -
nl80211_del_key(), and cfg80211_validate_key_settings().
Reported-by: syzbot+49d4cab497c2142ee170@xxxxxxxxxxxxxxxxxxxxxxxxx
Tested-by: syzbot+49d4cab497c2142ee170@xxxxxxxxxxxxxxxxxxxxxxxxx
Suggested-by: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
Signed-off-by: Anant Thazhemadam <anant.thazhemadam@xxxxxxxxx>
---
For the bug that was getting triggered, pairwise was true, and
the NL80211_EXT_FEATURE_BEACON_PROTECTION feature was set too.
The control logic for cfg80211_validate_key_settings() has been
designed keeping this also in mind.
net/wireless/core.h | 2 ++
net/wireless/nl80211.c | 7 ++++---
net/wireless/util.c | 27 ++++++++++++++++++++-------
3 files changed, 26 insertions(+), 10 deletions(-)
diff --git a/net/wireless/core.h b/net/wireless/core.h
index e3e9686859d4..7df91f940212 100644
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@ -433,6 +433,8 @@ void cfg80211_sme_abandon_assoc(struct wireless_dev *wdev);
/* internal helpers */
bool cfg80211_supported_cipher_suite(struct wiphy *wiphy, u32 cipher);
+bool cfg80211_valid_key_idx(struct cfg80211_registered_device *rdev,
+ int key_idx, bool pairwise);
int cfg80211_validate_key_settings(struct cfg80211_registered_device *rdev,
struct key_params *params, int key_idx,
bool pairwise, const u8 *mac_addr);
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index a77174b99b07..db36158911ae 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -4260,9 +4260,6 @@ static int nl80211_del_key(struct sk_buff *skb, struct genl_info *info)
if (err)
return err;
- if (key.idx < 0)
- return -EINVAL;
-
if (info->attrs[NL80211_ATTR_MAC])
mac_addr = nla_data(info->attrs[NL80211_ATTR_MAC]);
@@ -4278,6 +4275,10 @@ static int nl80211_del_key(struct sk_buff *skb, struct genl_info *info)
key.type != NL80211_KEYTYPE_GROUP)
return -EINVAL;
+ if (!cfg80211_valid_key_idx(rdev, key.idx,
+ key.type == NL80211_KEYTYPE_PAIRWISE))
+ return -EINVAL;
+
if (!rdev->ops->del_key)
return -EOPNOTSUPP;
diff --git a/net/wireless/util.c b/net/wireless/util.c
index f01746894a4e..07b17feb9b1e 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -272,18 +272,31 @@ bool cfg80211_supported_cipher_suite(struct wiphy *wiphy, u32 cipher)
return false;
}
-int cfg80211_validate_key_settings(struct cfg80211_registered_device *rdev,
- struct key_params *params, int key_idx,
- bool pairwise, const u8 *mac_addr)
+bool cfg80211_valid_key_idx(struct cfg80211_registered_device *rdev,
+ int key_idx, bool pairwise)
{
int max_key_idx = 5;
- if (wiphy_ext_feature_isset(&rdev->wiphy,
- NL80211_EXT_FEATURE_BEACON_PROTECTION) ||
- wiphy_ext_feature_isset(&rdev->wiphy,
- NL80211_EXT_FEATURE_BEACON_PROTECTION_CLIENT))
+ if (pairwise)
+ max_key_idx = 3;
+
+ else if (wiphy_ext_feature_isset(&rdev->wiphy,
+ NL80211_EXT_FEATURE_BEACON_PROTECTION) ||
+ wiphy_ext_feature_isset(&rdev->wiphy,
+ NL80211_EXT_FEATURE_BEACON_PROTECTION_CLIENT))
max_key_idx = 7;
+
if (key_idx < 0 || key_idx > max_key_idx)
+ return false;
+
+ return true;
+}
+
+int cfg80211_validate_key_settings(struct cfg80211_registered_device *rdev,
+ struct key_params *params, int key_idx,
+ bool pairwise, const u8 *mac_addr)
+{
+ if (!cfg80211_valid_key_idx(rdev, key_idx, pairwise))
return -EINVAL;
if (!pairwise && mac_addr && !(rdev->wiphy.flags & WIPHY_FLAG_IBSS_RSN))
--
2.25.1
