Commit 3ac10800 authored by Krzysztof Mazur's avatar Krzysztof Mazur Committed by David Woodhouse

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 <>
Cc: Chas Williams - CONTRACTOR <>
Signed-off-by: default avatarDavid Woodhouse <>
parent e41faed9
......@@ -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;
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)
skb = n;
if (skb == NULL)
if (skb == NULL) {
} 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;
case e_autodetect:
pr_debug("Trying to send without setting encaps!\n");
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;
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)
return ret;
* 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
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