| From | Jiri Slaby <> | Subject | [PATCH 3.12 003/113] net: possible use after free in dst_release | Date | Mon, 6 Mar 2017 10:10:27 +0100 |
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From: Francesco Ruggeri <fruggeri@aristanetworks.com>
3.12-stable review patch. If anyone has any objections, please let me know.
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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@arista.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Cc: Willy Tarreau <w@1wt.eu> Signed-off-by: Jiri Slaby <jslaby@suse.cz> --- 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 31344009de25..08c9a8f7b885 100644 --- a/net/core/dst.c +++ b/net/core/dst.c @@ -280,12 +280,13 @@ 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); } } -- 2.12.0
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