netdev - [PATCH AUTOSEL 4.19 02/16] cfg80211: call cfg80211_leave

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Date:   Mon, 21 Jun 2021 13:54:36 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Du Cheng <ducheng2@...il.com>,
        syzbot+105896fac213f26056f9@...kaller.appspotmail.com,
        Johannes Berg <johannes.berg@...el.com>,
        Sasha Levin <sashal@...nel.org>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19 02/16] cfg80211: call cfg80211_leave_ocb when switching away from OCB

From: Du Cheng <ducheng2@...il.com>

[ Upstream commit a64b6a25dd9f984ed05fade603a00e2eae787d2f ]

If the userland switches back-and-forth between NL80211_IFTYPE_OCB and
NL80211_IFTYPE_ADHOC via send_msg(NL80211_CMD_SET_INTERFACE), there is a
chance where the cleanup cfg80211_leave_ocb() is not called. This leads
to initialization of in-use memory (e.g. init u.ibss while in-use by
u.ocb) due to a shared struct/union within ieee80211_sub_if_data:

struct ieee80211_sub_if_data {
    ...
    union {
        struct ieee80211_if_ap ap;
        struct ieee80211_if_vlan vlan;
        struct ieee80211_if_managed mgd;
        struct ieee80211_if_ibss ibss; // <- shares address
        struct ieee80211_if_mesh mesh;
        struct ieee80211_if_ocb ocb; // <- shares address
        struct ieee80211_if_mntr mntr;
        struct ieee80211_if_nan nan;
    } u;
    ...
}

Therefore add handling of otype == NL80211_IFTYPE_OCB, during
cfg80211_change_iface() to perform cleanup when leaving OCB mode.

link to syzkaller bug:
https://syzkaller.appspot.com/bug?id=0612dbfa595bf4b9b680ff7b4948257b8e3732d5

Reported-by: syzbot+105896fac213f26056f9@...kaller.appspotmail.com
Signed-off-by: Du Cheng <ducheng2@...il.com>
Link: https://lore.kernel.org/r/20210428063941.105161-1-ducheng2@gmail.com
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/wireless/util.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/wireless/util.c b/net/wireless/util.c
index c4536468dfbe..e7be500b6452 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -965,6 +965,9 @@ int cfg80211_change_iface(struct cfg80211_registered_device *rdev,
 		case NL80211_IFTYPE_MESH_POINT:
 			/* mesh should be handled? */
 			break;
+		case NL80211_IFTYPE_OCB:
+			cfg80211_leave_ocb(rdev, dev);
+			break;
 		default:
 			break;
 		}
-- 
2.30.2