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: 27b75c95f1
("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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parent
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@ -280,10 +280,11 @@ void dst_release(struct dst_entry *dst)
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{
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if (dst) {
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int newrefcnt;
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unsigned short nocache = dst->flags & DST_NOCACHE;
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newrefcnt = atomic_dec_return(&dst->__refcnt);
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WARN_ON(newrefcnt < 0);
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if (!newrefcnt && unlikely(dst->flags & DST_NOCACHE))
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if (!newrefcnt && unlikely(nocache))
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call_rcu(&dst->rcu_head, dst_destroy_rcu);
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}
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}
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