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Commit 3ac10800 authored by Krzysztof Mazur's avatar Krzysztof Mazur Committed by David Woodhouse
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pppoatm: take ATM socket lock in pppoatm_send() 



The pppoatm_send() does not take any lock that will prevent concurrent
vcc_sendmsg(). This causes two problems:

	- there is no locking between checking the send queue size
	  with atm_may_send() and incrementing sk_wmem_alloc,
	  and the real queue size can be a little higher than sk_sndbuf

	- the vcc->sendmsg() can be called concurrently. I'm not sure
	  if it's allowed. Some drivers (eni, nicstar, ...) seem
	  to assume it will never happen.

Now pppoatm_send() takes ATM socket lock, the same that is used
in vcc_sendmsg() and other ATM socket functions. The pppoatm_send()
is called with BH disabled, so bh_lock_sock() is used instead
of lock_sock().

Signed-off-by: default avatarKrzysztof Mazur <krzysiek@podlesie.net>
Cc: Chas Williams - CONTRACTOR <chas@cmf.nrl.navy.mil>
Signed-off-by: default avatarDavid Woodhouse <David.Woodhouse@intel.com>
parent e41faed9

net/atm/pppoatm.c

+17 −2
Original line number Diff line number Diff line
@@ -272,10 +272,19 @@ static inline int pppoatm_may_send(struct pppoatm_vcc *pvcc, int size) 
static int pppoatm_send(struct ppp_channel *chan, struct sk_buff *skb)

{

	struct pppoatm_vcc *pvcc = chan_to_pvcc(chan);

	struct atm_vcc *vcc;

	int ret;



	ATM_SKB(skb)->vcc = pvcc->atmvcc;

	pr_debug("(skb=0x%p, vcc=0x%p)\n", skb, pvcc->atmvcc);

	if (skb->data[0] == '\0' && (pvcc->flags & SC_COMP_PROT))

		(void) skb_pull(skb, 1);



	vcc = ATM_SKB(skb)->vcc;

	bh_lock_sock(sk_atm(vcc));

	if (sock_owned_by_user(sk_atm(vcc)))

		goto nospace;



	switch (pvcc->encaps) {		/* LLC encapsulation needed */

	case e_llc:

		if (skb_headroom(skb) < LLC_LEN) {
@@ -288,8 +297,10 @@ static int pppoatm_send(struct ppp_channel *chan, struct sk_buff *skb) 
			}

			consume_skb(skb);

			skb = n;

			if (skb == NULL)

			if (skb == NULL) {

				bh_unlock_sock(sk_atm(vcc));

				return DROP_PACKET;

			}

		} else if (!pppoatm_may_send(pvcc, skb->truesize))

			goto nospace;

		memcpy(skb_push(skb, LLC_LEN), pppllc, LLC_LEN);
@@ -299,6 +310,7 @@ static int pppoatm_send(struct ppp_channel *chan, struct sk_buff *skb) 
			goto nospace;

		break;

	case e_autodetect:

		bh_unlock_sock(sk_atm(vcc));

		pr_debug("Trying to send without setting encaps!\n");

		kfree_skb(skb);

		return 1;
@@ -308,9 +320,12 @@ static int pppoatm_send(struct ppp_channel *chan, struct sk_buff *skb) 
	ATM_SKB(skb)->atm_options = ATM_SKB(skb)->vcc->atm_options;

	pr_debug("atm_skb(%p)->vcc(%p)->dev(%p)\n",

		 skb, ATM_SKB(skb)->vcc, ATM_SKB(skb)->vcc->dev);

	return ATM_SKB(skb)->vcc->send(ATM_SKB(skb)->vcc, skb)

	ret = ATM_SKB(skb)->vcc->send(ATM_SKB(skb)->vcc, skb)

	    ? DROP_PACKET : 1;

	bh_unlock_sock(sk_atm(vcc));

	return ret;

nospace:

	bh_unlock_sock(sk_atm(vcc));

	/*

	 * We don't have space to send this SKB now, but we might have

	 * already applied SC_COMP_PROT compression, so may need to undo