From 003b127e3c9e5bc83249e1106fd3de9da8dcf741 Mon Sep 17 00:00:00 2001 From: Francesco Ruggeri Date: Wed, 6 Jan 2016 00:18:48 -0800 Subject: net: possible use after free in dst_release [ 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 --- net/core/dst.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'net') diff --git a/net/core/dst.c b/net/core/dst.c index c07070544e3f..74d1ad1285d0 100644 --- a/net/core/dst.c +++ b/net/core/dst.c @@ -280,10 +280,11 @@ 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); } } -- cgit v1.2.3