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authorWei Wang <weiwan@google.com>2017-06-17 10:42:31 -0700
committerDavid S. Miller <davem@davemloft.net>2017-06-17 22:54:00 -0400
commit9df16efadd2a8a82731dc76ff656c771e261827f (patch)
treee43af92481dcf7517e8c7e086cfccecbc6bd0792 /include/net/route.h
parent95c47f9cf5e028d1ae77dc6c767c1edc8a18025b (diff)
ipv4: call dst_hold_safe() properly
This patch checks all the calls to dst_hold()/skb_dst_force()/dst_clone()/dst_use() to see if dst_hold_safe() is needed to avoid double free issue if dst gc is removed and dst_release() directly destroys dst when dst->__refcnt drops to 0. In tx path, TCP hold sk->sk_rx_dst ref count and also hold sock_lock(). UDP and other similar protocols always hold refcount for skb->_skb_refdst. So both paths seem to be safe. In rx path, as it is lockless and skb_dst_set_noref() is likely to be used, dst_hold_safe() should always be used when trying to hold dst. In the routing code, if dst is held during an rcu protected session, it is necessary to call dst_hold_safe() as the current dst might be in its rcu grace period. Signed-off-by: Wei Wang <weiwan@google.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net/route.h')
-rw-r--r--include/net/route.h4
1 files changed, 3 insertions, 1 deletions
diff --git a/include/net/route.h b/include/net/route.h
index 08e689f23365..cb0a76d9dde1 100644
--- a/include/net/route.h
+++ b/include/net/route.h
@@ -190,7 +190,9 @@ static inline int ip_route_input(struct sk_buff *skb, __be32 dst, __be32 src,
rcu_read_lock();
err = ip_route_input_noref(skb, dst, src, tos, devin);
if (!err)
- skb_dst_force(skb);
+ skb_dst_force_safe(skb);
+ if (!skb_dst(skb))
+ err = -EINVAL;
rcu_read_unlock();
return err;