Commit d69bbf88 authored Nov 09, 2015 by Eric Dumazet Committed by David S. Miller Nov 09, 2015

net: fix a race in dst_release()



Only cpu seeing dst refcount going to 0 can safely
dereference dst->flags.

Otherwise an other cpu might already have freed the dst.

Fixes: 27b75c95 ("net: avoid RCU for NOCACHE dst")
Reported-by: Greg Thelen <gthelen@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 8c94ddbc

net/core/dst.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -306,7 +306,7 @@ void dst_release(struct dst_entry *dst)
		if (unlikely(newrefcnt < 0))
		net_warn_ratelimited("%s: dst:%p refcnt:%d\n",
		__func__, dst, newrefcnt);
		if (unlikely(dst->flags & DST_NOCACHE) && !newrefcnt)
		if (!newrefcnt && unlikely(dst->flags & DST_NOCACHE))
		call_rcu(&dst->rcu_head, dst_destroy_rcu);
		}
		}