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

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Date:	Sat, 19 May 2007 12:33:04 +0200 (MEST)
From:	Andrea Righi <righiandr@...rs.sourceforge.net>
To:	Bernd Eckenfels <ecki@...a.inka.de>
Cc:	linux-kernel@...r.kernel.org, Rik van Riel <riel@...hat.com>,
	linux-mm@...ck.org, Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH 1/2] limit print_fatal_signal() rate (was: [RFC] log out-of-virtual-memory
 events)

Bernd Eckenfels wrote:
> In article <464DCEAB.3090905@...rs.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@...eca.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__
-
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