[PATCH 1/2] limit print_fatal_signal() rate (was: [RFC] log out-of-virtual-memory events)

[Andrea Righi <righiandr@users.sourceforge.net>]

Bernd Eckenfels wrote:
> In article <464DCEAB.3090905@users.sourceforge.net> you wrote:
>>        printk("%s/%d: potentially unexpected fatal signal %d.\n",
>>                current->comm, current->pid, signr);
> 
> can we have both KERN_WARNING please?
> 
> Gruss
> Bernd

Depends on print_fatal_signals patch.

---

Limit the rate of print_fatal_signal() to avoid potential denial-of-service
attacks.

Signed-off-by: Andrea Righi <a.righi@cineca.it>

diff -urpN linux-2.6.22-rc1-mm1/kernel/signal.c linux-2.6.22-rc1-mm1-vm-log-enomem/kernel/signal.c
--- linux-2.6.22-rc1-mm1/kernel/signal.c	2007-05-19 11:25:24.000000000 +0200
+++ linux-2.6.22-rc1-mm1-vm-log-enomem/kernel/signal.c	2007-05-19 11:30:00.000000000 +0200
@@ -790,7 +790,10 @@ static void print_vmas(void)
 
 static void print_fatal_signal(struct pt_regs *regs, int signr)
 {
-	printk("%s/%d: potentially unexpected fatal signal %d.\n",
+	if (unlikely(!printk_ratelimit()))
+		return;
+
+	printk(KERN_WARNING "%s/%d: potentially unexpected fatal signal %d.\n",
 		current->comm, current->pid, signr);
 
 #ifdef __i386__