Re: [PATCH] pppoatm: don't send frames to destroyed vcc
From: Krzysztof Mazur <hidden>
Date: 2012-10-06 15:46:10
Also in:
lkml
Subsystem:
atm, networking [general], ppp over atm (rfc 2364), the rest · Maintainers:
Chas Williams, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Mitchell Blank Jr, Linus Torvalds
On Sat, Oct 06, 2012 at 05:38:04PM +0200, Krzysztof Mazur wrote:
On Sat, Oct 06, 2012 at 02:32:50PM +0100, David Woodhouse wrote:quoted
On Sat, 2012-10-06 at 14:19 +0200, Krzysztof Mazur wrote:quoted
Now pppoatm_send(), like vcc_sendmsg(), checks for vcc flags that indicate that vcc is not ready.And what locking prevents the flag from being set immediately after we check it?nothing, this patch should fix this.
I think there is another problem here. The pppoatm gets a reference to atmvcc, but I don't see anything that protects against removal of that vcc. The vcc uses vcc->sk socket for reference counting, so sock_hold() and sock_put() should be used by pppoatm.
diff --git a/net/atm/pppoatm.c b/net/atm/pppoatm.c
index 29afc68..126f57f 100644
--- a/net/atm/pppoatm.c
+++ b/net/atm/pppoatm.c@@ -154,6 +154,7 @@ static void pppoatm_unassign_vcc(struct atm_vcc *atmvcc) tasklet_kill(&pvcc->wakeup_tasklet); ppp_unregister_channel(&pvcc->chan); atmvcc->user_back = NULL; + sock_put(sk_atm(pvcc->atmvcc)); kfree(pvcc); /* Gee, I hope we have the big kernel lock here... */ module_put(THIS_MODULE);
@@ -371,6 +372,7 @@ static int pppoatm_assign_vcc(struct atm_vcc *atmvcc, void __user *arg) if (pvcc == NULL) return -ENOMEM; pvcc->atmvcc = atmvcc; + sock_hold(sk_atm(atmvcc)); /* Maximum is zero, so that we can use atomic_inc_not_zero() */ atomic_set(&pvcc->inflight, NONE_INFLIGHT);
@@ -385,6 +387,7 @@ static int pppoatm_assign_vcc(struct atm_vcc *atmvcc, void __user *arg) pvcc->wakeup_tasklet.data = (unsigned long) &pvcc->chan; err = ppp_register_channel(&pvcc->chan); if (err != 0) { + sock_put(sk_atm(atmvcc)); kfree(pvcc); return err; }
--
Krzysiek