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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: Krzysztof Mazur <krzysiek@podlesie.net>
Cc: Chas Williams - CONTRACTOR <chas@cmf.nrl.navy.mil>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
This commit is contained in:
Krzysztof Mazur 2012-11-06 23:17:00 +01:00 committed by David Woodhouse
parent e41faed9cd
commit 3ac108006f
1 changed files with 17 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
net/atm/pppoatm.c
View File

@ -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