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authorFrancesco Ruggeri <fruggeri@aristanetworks.com>2016-01-06 00:18:48 -0800
committerDavid S. Miller <davem@davemloft.net>2016-01-06 15:00:27 -0500
commit07a5d38453599052aff0877b16bb9c1585f08609 (patch)
tree2e548a87ab4e08e97da4aabb6387f63d2cf06a98
parent73c20a8b7245273125cfe92c4b46e6fdb568a801 (diff)
downloadleg-kernel-07a5d38453599052aff0877b16bb9c1585f08609.tar.gz
net: possible use after free in dst_release
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 <fruggeri@arista.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/core/dst.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/net/core/dst.c b/net/core/dst.c
index e6dc77252fe9..a1656e3b8d72 100644
--- a/net/core/dst.c
+++ b/net/core/dst.c
@@ -301,12 +301,13 @@ void dst_release(struct dst_entry *dst)
{
if (dst) {
int newrefcnt;
+ unsigned short nocache = dst->flags & DST_NOCACHE;
newrefcnt = atomic_dec_return(&dst->__refcnt);
if (unlikely(newrefcnt < 0))
net_warn_ratelimited("%s: dst:%p refcnt:%d\n",
__func__, dst, newrefcnt);
- if (!newrefcnt && unlikely(dst->flags & DST_NOCACHE))
+ if (!newrefcnt && unlikely(nocache))
call_rcu(&dst->rcu_head, dst_destroy_rcu);
}
}