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| author | Cong Wang <xiyou.wangcong@gmail.com> | 2018-08-07 12:41:38 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-08-07 15:54:00 -0700 |
| commit | 0dcb82254d65f72333aa50ad626d1e9665ad093b (patch) | |
| tree | 0624bb5c365884b956d4abaf79d50e87a1406762 /net/llc | |
| parent | 61ef4b07fcdc30535889990cf4229766502561cf (diff) | |
| download | lwn-0dcb82254d65f72333aa50ad626d1e9665ad093b.tar.gz lwn-0dcb82254d65f72333aa50ad626d1e9665ad093b.zip | |
llc: use refcount_inc_not_zero() for llc_sap_find()
llc_sap_put() decreases the refcnt before deleting sap
from the global list. Therefore, there is a chance
llc_sap_find() could find a sap with zero refcnt
in this global list.
Close this race condition by checking if refcnt is zero
or not in llc_sap_find(), if it is zero then it is being
removed so we can just treat it as gone.
Reported-by: <syzbot+278893f3f7803871f7ce@syzkaller.appspotmail.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/llc')
| -rw-r--r-- | net/llc/llc_core.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/net/llc/llc_core.c b/net/llc/llc_core.c index 89041260784c..260b3dc1b4a2 100644 --- a/net/llc/llc_core.c +++ b/net/llc/llc_core.c @@ -73,8 +73,8 @@ struct llc_sap *llc_sap_find(unsigned char sap_value) rcu_read_lock_bh(); sap = __llc_sap_find(sap_value); - if (sap) - llc_sap_hold(sap); + if (!sap || !llc_sap_hold_safe(sap)) + sap = NULL; rcu_read_unlock_bh(); return sap; } |