From: Anant Thazhemadam <anant.thazhemadam@xxxxxxxxx> commit 2d9463083ce92636a1bdd3e30d1236e3e95d859e upstream. 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> Link: https://lore.kernel.org/r/20201204215825.129879-1-anant.thazhemadam@xxxxxxxxx Cc: stable@xxxxxxxxxxxxxxx [also disallow IGTK key IDs if no IGTK cipher is supported] Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/wireless/core.h | 2 + net/wireless/nl80211.c | 7 +++--- net/wireless/util.c | 51 +++++++++++++++++++++++++++++++++++++++++-------- 3 files changed, 49 insertions(+), 11 deletions(-) --- a/net/wireless/core.h +++ b/net/wireless/core.h @@ -433,6 +433,8 @@ void cfg80211_sme_abandon_assoc(struct w /* 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); --- a/net/wireless/nl80211.c +++ b/net/wireless/nl80211.c @@ -4260,9 +4260,6 @@ static int nl80211_del_key(struct sk_buf 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_buf 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; --- a/net/wireless/util.c +++ b/net/wireless/util.c @@ -272,18 +272,53 @@ bool cfg80211_supported_cipher_suite(str 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) +static bool +cfg80211_igtk_cipher_supported(struct cfg80211_registered_device *rdev) +{ + struct wiphy *wiphy = &rdev->wiphy; + int i; + + for (i = 0; i < wiphy->n_cipher_suites; i++) { + switch (wiphy->cipher_suites[i]) { + case WLAN_CIPHER_SUITE_AES_CMAC: + case WLAN_CIPHER_SUITE_BIP_CMAC_256: + case WLAN_CIPHER_SUITE_BIP_GMAC_128: + case WLAN_CIPHER_SUITE_BIP_GMAC_256: + return true; + } + } + + return false; +} + +bool cfg80211_valid_key_idx(struct cfg80211_registered_device *rdev, + int key_idx, bool pairwise) { - int max_key_idx = 5; + int max_key_idx; - 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; + else if (cfg80211_igtk_cipher_supported(rdev)) + max_key_idx = 5; + else + max_key_idx = 3; + 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))
