From da92b194cc36b5dc1fbd85206aeeffd80bee0c39 Mon Sep 17 00:00:00 2001 From: Richard Cochran Date: Fri, 21 Oct 2011 00:49:15 +0000 Subject: net: hold sock reference while processing tx timestamps The pair of functions, * skb_clone_tx_timestamp() * skb_complete_tx_timestamp() were designed to allow timestamping in PHY devices. The first function, called during the MAC driver's hard_xmit method, identifies PTP protocol packets, clones them, and gives them to the PHY device driver. The PHY driver may hold onto the packet and deliver it at a later time using the second function, which adds the packet to the socket's error queue. As pointed out by Johannes, nothing prevents the socket from disappearing while the cloned packet is sitting in the PHY driver awaiting a timestamp. This patch fixes the issue by taking a reference on the socket for each such packet. In addition, the comments regarding the usage of these function are expanded to highlight the rule that PHY drivers must use skb_complete_tx_timestamp() to release the packet, in order to release the socket reference, too. These functions first appeared in v2.6.36. Reported-by: Johannes Berg Signed-off-by: Richard Cochran Cc: Signed-off-by: Eric Dumazet Reviewed-by: Johannes Berg Signed-off-by: David S. Miller --- net/core/timestamping.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) (limited to 'net/core') diff --git a/net/core/timestamping.c b/net/core/timestamping.c index 98a52640e7cd..82fb28857b64 100644 --- a/net/core/timestamping.c +++ b/net/core/timestamping.c @@ -57,9 +57,13 @@ void skb_clone_tx_timestamp(struct sk_buff *skb) case PTP_CLASS_V2_VLAN: phydev = skb->dev->phydev; if (likely(phydev->drv->txtstamp)) { + if (!atomic_inc_not_zero(&sk->sk_refcnt)) + return; clone = skb_clone(skb, GFP_ATOMIC); - if (!clone) + if (!clone) { + sock_put(sk); return; + } clone->sk = sk; phydev->drv->txtstamp(phydev, clone, type); } @@ -77,8 +81,11 @@ void skb_complete_tx_timestamp(struct sk_buff *skb, struct sock_exterr_skb *serr; int err; - if (!hwtstamps) + if (!hwtstamps) { + sock_put(sk); + kfree_skb(skb); return; + } *skb_hwtstamps(skb) = *hwtstamps; serr = SKB_EXT_ERR(skb); @@ -87,6 +94,7 @@ void skb_complete_tx_timestamp(struct sk_buff *skb, serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING; skb->sk = NULL; err = sock_queue_err_skb(sk, skb); + sock_put(sk); if (err) kfree_skb(skb); } -- cgit v1.2.3