Re: [PATCH net] phonet: properly unshare skbs inphonet_rcv()
From: Rémi Denis-Courmont <hidden>
Date: 2016-01-13 12:33:48
Le 2016-01-12 18:58, Eric Dumazet a écrit :
From: Eric Dumazet <edumazet@google.com>
Ivaylo Dimitrov reported a regression caused by commit 7866a621043f
("dev: add per net_device packet type chains").
skb->dev becomes NULL and we crash in __netif_receive_skb_core().
Before above commit, different kind of bugs or corruptions could
happen
without major crash.Hmm... was that always a problem then, or did it get introduced earlier? I thought it was impossible for skb to be shared on PF-recv callback way back.
quoted hunk ↗ jump to hunk
But the root cause is that phonet_rcv() can queue skb without checking if skb is shared or not. Many thanks to Ivaylo Dimitrov for his help, diagnosis and tests. Reported-by: Ivaylo Dimitrov <redacted> Tested-by: Ivaylo Dimitrov <redacted> Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Remi Denis-Courmont <courmisch@gmail.com> --- net/phonet/af_phonet.c | 4 ++++ 1 file changed, 4 insertions(+)diff --git a/net/phonet/af_phonet.c b/net/phonet/af_phonet.c index 10d42f3220ab..f925753668a7 100644 --- a/net/phonet/af_phonet.c +++ b/net/phonet/af_phonet.c@@ -377,6 +377,10 @@ static int phonet_rcv(struct sk_buff *skb,struct net_device *dev, struct sockaddr_pn sa; u16 len; + skb = skb_share_check(skb, GFP_ATOMIC); + if (!skb) + return NET_RX_DROP; + /* check we have at least a full Phonet header */ if (!pskb_pull(skb, sizeof(struct phonethdr))) goto out;
Ack, thanks. -- Rémi Denis-Courmont http://www.remlab.net/