4.2.8-ckt2 -stable review patch. If anyone has any objections, please let me know.
---8<------------------------------------------------------------
From: Francesco Ruggeri <fruggeri@xxxxxxxxxxxxxxxxxx>
commit 07a5d38453599052aff0877b16bb9c1585f08609 upstream.
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@xxxxxxxxxx>
Acked-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
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 cc4a086..27e030f 100644
--- a/net/core/dst.c
+++ b/net/core/dst.c
@@ -282,12 +282,13 @@ 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);
}
}
--
1.9.1
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