cfg80211: call cfg80211_leave_ocb when switching away from OCB

[ 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@syzkaller.appspotmail.com
Signed-off-by: Du Cheng <ducheng2@gmail.com>
Link: https://lore.kernel.org/r/20210428063941.105161-1-ducheng2@gmail.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/wireless/util.c b/net/wireless/util.c
index 2731267..4fb8d1b 100644 (file)
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -1059,6 +1059,9 @@ 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;
                }