From 1d5a026a4e6a3ab8f0c7f1fd00cc7d895bf5fa57 Mon Sep 17 00:00:00 2001 From: Francesco Ruggeri Date: Wed, 6 Jan 2016 00:18:48 -0800 Subject: [PATCH] net: possible use after free in dst_release Orabug: 23330551 [ Upstream commit 07a5d38453599052aff0877b16bb9c1585f08609 ] dst_release should not access dst->flags after decrementing __refcnt to 0. The dst_entry may be in dst_busy_list and dst_gc_task may dst_destroy it before dst_release gets a chance to access dst->flags. Fixes: d69bbf88c8d0 ("net: fix a race in dst_release()") Fixes: 27b75c95f10d ("net: avoid RCU for NOCACHE dst") Signed-off-by: Francesco Ruggeri Acked-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman (cherry picked from commit 8f5cd6eea8115c6a4153268508369b81f84e9dce) Signed-off-by: Dan Duval --- net/core/dst.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/core/dst.c b/net/core/dst.c index f8db4032d45a..540066cb33ef 100644 --- a/net/core/dst.c +++ b/net/core/dst.c @@ -282,10 +282,11 @@ void dst_release(struct dst_entry *dst) { if (dst) { int newrefcnt; + unsigned short nocache = dst->flags & DST_NOCACHE; newrefcnt = atomic_dec_return(&dst->__refcnt); WARN_ON(newrefcnt < 0); - if (!newrefcnt && unlikely(dst->flags & DST_NOCACHE)) + if (!newrefcnt && unlikely(nocache)) call_rcu(&dst->rcu_head, dst_destroy_rcu); } } -- 2.50.1