Re: [PATCH] 2.4.18 Eicon ISDN driver fix.

[Armin Schindler]

The patch below fixes the race condition with copy_to_user and will
not introduce a new race. What can happen is that two reader-processes
may get mixed-up messages, but more than one reader isn't allowed here
anyway.

Please apply this patch to 2.4 and 2.2, it works for both.

Thanx,
Armin

On 26 Feb 2002, petter wahlman wrote:
> The following code is calling a possibly blocking operation while
> holding a spinlock.
>
>
> Petter Wahlman

--- linux-2.4.18/drivers/isdn/eicon/eicon_mod.c Fri Dec 21 18:41:54 2001
+++ linux-2.4.18-pw/drivers/isdn/eicon/eicon_mod.c      Mon Feb 25
23:45:05 2002
@@ -665,8 +665,11 @@
                        else
                                cnt = skb->len;

-                       if (user)
+                       if (user) {
+                               spin_unlock_irqrestore(&eicon_lock,
flags);
                                copy_to_user(p, skb->data, cnt);
+                               spin_lock_irqsave(&eicon_lock, flags);
+                       }
                        else
                                memcpy(p, skb->data, cnt);