From: Anant Thazhemadam anant.thazhemadam@gmail.com

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@syzkaller.appspotmail.com Tested-by: syzbot+49d4cab497c2142ee170@syzkaller.appspotmail.com Suggested-by: Johannes Berg johannes@sipsolutions.net Signed-off-by: Anant Thazhemadam anant.thazhemadam@gmail.com Link: https://lore.kernel.org/r/20201204215825.129879-1-anant.thazhemadam@gmail.co... Cc: stable@vger.kernel.org [also disallow IGTK key IDs if no IGTK cipher is supported] Signed-off-by: Johannes Berg johannes.berg@intel.com Signed-off-by: Zubin Mithra zsm@chromium.org --- * Syzkaller triggered an OOB-read with the following stacktrace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0xef/0x160 lib/dump_stack.c:118 print_address_description.constprop.0+0x17/0x311 mm/kasan/report.c:374 __kasan_report+0x145/0x18c mm/kasan/report.c:506 kasan_report+0x10/0x16 mm/kasan/common.c:634 ieee80211_key_free+0xb8/0xef net/mac80211/key.c:844 ieee80211_del_key+0x324/0x354 net/mac80211/cfg.c:532 rdev_del_key net/wireless/rdev-ops.h:107 [inline] nl80211_del_key+0x636/0x758 net/wireless/nl80211.c:4081 genl_family_rcv_msg+0xaa4/0xbb1 net/netlink/genetlink.c:629 genl_rcv_msg+0xce/0x127 net/netlink/genetlink.c:654 netlink_rcv_skb+0x23d/0x318 net/netlink/af_netlink.c:2478 genl_rcv+0x24/0x31 net/netlink/genetlink.c:665 netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline] netlink_unicast+0x432/0x556 net/netlink/af_netlink.c:1329 netlink_sendmsg+0x943/0x9a8 net/netlink/af_netlink.c:1918 sock_sendmsg_nosec net/socket.c:638 [inline] sock_sendmsg+0xd5/0x10c net/socket.c:658 ____sys_sendmsg+0x4ea/0x641 net/socket.c:2298 ___sys_sendmsg+0x14a/0x1a9 net/socket.c:2352 __sys_sendmsg+0xf1/0x181 net/socket.c:2398 do_syscall_64+0x106/0x13f arch/x86/entry/common.c:299 entry_SYSCALL_64_after_hwframe+0x49/0xbe

* This commit is present in 5.10.y. The crash does not occur on 4.14.y and older.

* Tests run: syzkaller reproducer, Chrome OS tryjobs

net/wireless/core.h | 2 ++ net/wireless/nl80211.c | 7 ++++--- net/wireless/util.c | 39 ++++++++++++++++++++++++++++++++++++++- 3 files changed, 44 insertions(+), 4 deletions(-)

diff --git a/net/wireless/core.h b/net/wireless/core.h index d83c8e009448..17621d22fb17 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 5bb2316befb9..7b170ed6923e 100644 --- a/net/wireless/nl80211.c +++ b/net/wireless/nl80211.c @@ -3979,9 +3979,6 @@ 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]);

@@ -3997,6 +3994,10 @@ 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 82244e2fc1f5..4eae6ad32851 100644 --- a/net/wireless/util.c +++ b/net/wireless/util.c @@ -229,11 +229,48 @@ bool cfg80211_supported_cipher_suite(struct wiphy *wiphy, u32 cipher) return false; }

+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; + + if (pairwise) + max_key_idx = 3; + 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 (key_idx < 0 || key_idx > 5) + if (!cfg80211_valid_key_idx(rdev, key_idx, pairwise)) return -EINVAL;

if (!pairwise && mac_addr && !(rdev->wiphy.flags & WIPHY_FLAG_IBSS_RSN))