The pppoatm_send() calls vcc->send() and now also checks for some vcc flags that indicate destroyed vcc without proper locking.
The vcc_sendmsg() uses lock_sock(sk). This lock is used by vcc_release(), so vcc_destroy_socket() will not be called between check and during ->send(). The vcc_release_async() sets ATM_VF_CLOSE, but it should be safe to call ->send() after it, because vcc->dev->ops->close() is not called. The pppoatm_send() is called with BH disabled, so bh_lock_sock() should be used instead of lock_sock(). Signed-off-by: Krzysztof Mazur <[email protected]> Cc: David Woodhouse <[email protected]> --- net/atm/pppoatm.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/net/atm/pppoatm.c b/net/atm/pppoatm.c index 0dcb5dc..e3b2d69 100644 --- a/net/atm/pppoatm.c +++ b/net/atm/pppoatm.c @@ -270,6 +270,7 @@ 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); @@ -304,17 +305,24 @@ static int pppoatm_send(struct ppp_channel *chan, struct sk_buff *skb) } vcc = ATM_SKB(skb)->vcc; + bh_lock_sock(sk_atm(vcc)); + if (sock_owned_by_user(sk_atm(vcc))) + goto nospace_unlock_sock; if (test_bit(ATM_VF_RELEASED, &vcc->flags) || test_bit(ATM_VF_CLOSE, &vcc->flags) || !test_bit(ATM_VF_READY, &vcc->flags)) - goto nospace; + goto nospace_unlock_sock; atomic_add(skb->truesize, &sk_atm(ATM_SKB(skb)->vcc)->sk_wmem_alloc); 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_unlock_sock: + bh_unlock_sock(sk_atm(vcc)); nospace: /* * We don't have space to send this SKB now, but we might have -- 1.8.0.2.g35080e9 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
