From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
To: netdev@vger.kernel.org, "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>,
Herbert Xu <herbert@gondor.apana.org.au>
Subject: [PATCH] netlink: enable skb header refcounting before sending first broadcast
Date: Fri, 10 Jul 2015 14:51:41 +0300 [thread overview]
Message-ID: <20150710115141.12980.88829.stgit@buzz> (raw)
This fixes race between non-atomic updates of adjacent bit-fields:
skb->cloned could be lost because netlink broadcast clones skb after
sending it to the first listener who sets skb->peeked at the same skb.
As a result atomic refcounting of skb header stays disabled and
skb_release_data() frees it twice. Race leads to double-free in kmalloc-xxx.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Fixes: b19372273164 ("net: reorganize sk_buff for faster __copy_skb_header()")
---
net/netlink/af_netlink.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index dea925388a5b..921e0d8dfe3a 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -2028,6 +2028,12 @@ int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb, u32 portid
info.tx_filter = filter;
info.tx_data = filter_data;
+ /* Enable atomic refcounting in skb_release_data() before first send:
+ * non-atomic set of that bit-field in __skb_clone() could race with
+ * __skb_recv_datagram() which touches the same set of bit-fields.
+ */
+ skb->cloned = 1;
+
/* While we sleep in clone, do not allow to change socket list */
netlink_lock_table();
next reply other threads:[~2015-07-10 11:51 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-10 11:51 Konstantin Khlebnikov [this message]
2015-07-10 13:49 ` [PATCH] netlink: enable skb header refcounting before sending first broadcast Eric Dumazet
2015-07-10 14:08 ` Konstantin Khlebnikov
2015-07-13 7:23 ` Herbert Xu
2015-07-13 8:04 ` net: Clone skb before setting peeked flag Herbert Xu
2015-07-15 23:13 ` David Miller
2015-07-13 8:05 ` [PATCH] netlink: enable skb header refcounting before sending first broadcast Eric Dumazet
2015-07-13 8:10 ` Herbert Xu
2015-07-13 8:22 ` Eric Dumazet
2015-07-13 8:25 ` Herbert Xu
2015-07-13 8:28 ` Eric Dumazet
2015-07-13 8:31 ` Herbert Xu
2015-07-13 12:01 ` net: Fix skb csum races when peeking Herbert Xu
2015-07-13 14:25 ` Herbert Xu
2015-07-14 6:11 ` Eric Dumazet
2015-07-15 23:14 ` David Miller
2015-07-13 8:54 ` [PATCH] netlink: enable skb header refcounting before sending first broadcast Konstantin Khlebnikov
2015-07-13 9:04 ` Herbert Xu
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