From: Andrea Righi <righiandr@users.sourceforge.net>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Bernd Eckenfels <ecki@lina.inka.de>,
linux-kernel@vger.kernel.org, Rik van Riel <riel@redhat.com>,
linux-mm@kvack.org, Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH 1/2] limit print_fatal_signal() rate
Date: Mon, 21 May 2007 12:44:20 +0200 (MEST) [thread overview]
Message-ID: <465177E9.3060601@users.sourceforge.net> (raw)
In-Reply-To: <20070520203123.5cde3224.akpm@linux-foundation.org>
Andrew Morton wrote:
> Well OK. But vdso-print-fatal-signals.patch is designated not-for-mainline
> anyway.
>
> I think the DoS which you identify has been available for a very long time
> on ia64, x86_64 and perhaps others.
>
For the mainline a fix could be the following...
---
Limit the rate of the kernel logging for the segfaults of user applications, to
avoid potential message floods or denial-of-service attacks.
Signed-off-by: Andrea Righi <a.righi@cineca.it>
diff -urpN linux-2.6.22-rc2/arch/avr32/mm/fault.c linux-2.6.22-rc2-limit-segfaults-printk-rate/arch/avr32/mm/fault.c
--- linux-2.6.22-rc2/arch/avr32/mm/fault.c 2007-05-19 13:11:30.000000000 +0200
+++ linux-2.6.22-rc2-limit-segfaults-printk-rate/arch/avr32/mm/fault.c 2007-05-21 11:48:37.000000000 +0200
@@ -158,7 +158,7 @@ bad_area:
up_read(&mm->mmap_sem);
if (user_mode(regs)) {
- if (exception_trace)
+ if (exception_trace && printk_ratelimit())
printk("%s%s[%d]: segfault at %08lx pc %08lx "
"sp %08lx ecr %lu\n",
is_init(tsk) ? KERN_EMERG : KERN_INFO,
diff -urpN linux-2.6.22-rc2/arch/x86_64/mm/fault.c linux-2.6.22-rc2-limit-segfaults-printk-rate/arch/x86_64/mm/fault.c
--- linux-2.6.22-rc2/arch/x86_64/mm/fault.c 2007-05-21 11:42:07.000000000 +0200
+++ linux-2.6.22-rc2-limit-segfaults-printk-rate/arch/x86_64/mm/fault.c 2007-05-21 11:45:55.000000000 +0200
@@ -489,7 +489,8 @@ bad_area_nosemaphore:
(address >> 32))
return;
- if (exception_trace && unhandled_signal(tsk, SIGSEGV)) {
+ if (exception_trace && unhandled_signal(tsk, SIGSEGV) &&
+ printk_ratelimit()) {
printk(
"%s%s[%d]: segfault at %016lx rip %016lx rsp %016lx error %lx\n",
tsk->pid > 1 ? KERN_INFO : KERN_EMERG,
WARNING: multiple messages have this Message-ID (diff)
From: Andrea Righi <righiandr@users.sourceforge.net>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Bernd Eckenfels <ecki@lina.inka.de>,
linux-kernel@vger.kernel.org, Rik van Riel <riel@redhat.com>,
linux-mm@kvack.org, Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH 1/2] limit print_fatal_signal() rate
Date: Mon, 21 May 2007 12:44:20 +0200 (MEST) [thread overview]
Message-ID: <465177E9.3060601@users.sourceforge.net> (raw)
In-Reply-To: <20070520203123.5cde3224.akpm@linux-foundation.org>
Andrew Morton wrote:
> Well OK. But vdso-print-fatal-signals.patch is designated not-for-mainline
> anyway.
>
> I think the DoS which you identify has been available for a very long time
> on ia64, x86_64 and perhaps others.
>
For the mainline a fix could be the following...
---
Limit the rate of the kernel logging for the segfaults of user applications, to
avoid potential message floods or denial-of-service attacks.
Signed-off-by: Andrea Righi <a.righi@cineca.it>
diff -urpN linux-2.6.22-rc2/arch/avr32/mm/fault.c linux-2.6.22-rc2-limit-segfaults-printk-rate/arch/avr32/mm/fault.c
--- linux-2.6.22-rc2/arch/avr32/mm/fault.c 2007-05-19 13:11:30.000000000 +0200
+++ linux-2.6.22-rc2-limit-segfaults-printk-rate/arch/avr32/mm/fault.c 2007-05-21 11:48:37.000000000 +0200
@@ -158,7 +158,7 @@ bad_area:
up_read(&mm->mmap_sem);
if (user_mode(regs)) {
- if (exception_trace)
+ if (exception_trace && printk_ratelimit())
printk("%s%s[%d]: segfault at %08lx pc %08lx "
"sp %08lx ecr %lu\n",
is_init(tsk) ? KERN_EMERG : KERN_INFO,
diff -urpN linux-2.6.22-rc2/arch/x86_64/mm/fault.c linux-2.6.22-rc2-limit-segfaults-printk-rate/arch/x86_64/mm/fault.c
--- linux-2.6.22-rc2/arch/x86_64/mm/fault.c 2007-05-21 11:42:07.000000000 +0200
+++ linux-2.6.22-rc2-limit-segfaults-printk-rate/arch/x86_64/mm/fault.c 2007-05-21 11:45:55.000000000 +0200
@@ -489,7 +489,8 @@ bad_area_nosemaphore:
(address >> 32))
return;
- if (exception_trace && unhandled_signal(tsk, SIGSEGV)) {
+ if (exception_trace && unhandled_signal(tsk, SIGSEGV) &&
+ printk_ratelimit()) {
printk(
"%s%s[%d]: segfault at %016lx rip %016lx rsp %016lx error %lx\n",
tsk->pid > 1 ? KERN_INFO : KERN_EMERG,
--
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next prev parent reply other threads:[~2007-05-21 10:44 UTC|newest]
Thread overview: 103+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-17 16:24 [RFC] log out-of-virtual-memory events Andrea Righi
2007-05-17 16:24 ` Andrea Righi
2007-05-17 18:22 ` Rik van Riel
2007-05-17 18:22 ` Rik van Riel
2007-05-18 6:28 ` signals logged / " Jan Engelhardt
2007-05-18 6:28 ` Jan Engelhardt
2007-05-18 11:47 ` Andi Kleen
2007-05-18 11:47 ` Andi Kleen
2007-05-19 7:46 ` Jan Engelhardt
2007-05-19 7:46 ` Jan Engelhardt
2007-05-19 9:35 ` Andrea Righi
2007-05-19 9:35 ` Andrea Righi
2007-05-19 10:06 ` Jan Engelhardt
2007-05-19 10:06 ` Jan Engelhardt
2007-05-19 10:16 ` Andrea Righi
2007-05-19 10:16 ` Andrea Righi
2007-05-20 0:14 ` Folkert van Heusden
2007-05-20 0:14 ` Folkert van Heusden
2007-05-20 3:55 ` Eric Dumazet
2007-05-20 3:55 ` Eric Dumazet
2007-05-20 11:21 ` Folkert van Heusden
2007-05-20 11:21 ` Folkert van Heusden
2007-05-20 16:08 ` Stephen Hemminger
2007-05-20 16:08 ` Stephen Hemminger
2007-05-20 16:12 ` Folkert van Heusden
2007-05-20 16:12 ` Folkert van Heusden
2007-05-20 20:38 ` Jan Engelhardt
2007-05-20 20:38 ` Jan Engelhardt
2007-05-20 20:55 ` Folkert van Heusden
2007-05-20 20:55 ` Folkert van Heusden
2007-05-20 21:14 ` Andi Kleen
2007-05-20 21:14 ` Andi Kleen
2007-05-20 21:20 ` Folkert van Heusden
2007-05-20 21:20 ` Folkert van Heusden
2007-05-20 21:23 ` Folkert van Heusden
2007-05-20 21:23 ` Folkert van Heusden
2007-05-20 22:24 ` Andi Kleen
2007-05-20 22:24 ` Andi Kleen
2007-05-20 22:22 ` Jeff Dike
2007-05-20 22:22 ` Jeff Dike
2007-05-21 11:26 ` Gábor Lénárt
2007-05-21 10:45 ` Andrea Righi
2007-05-21 10:45 ` Andrea Righi
2007-05-21 11:04 ` Folkert van Heusden
2007-05-21 11:04 ` Folkert van Heusden
2007-05-21 12:30 ` Jan Engelhardt
2007-05-21 12:30 ` Jan Engelhardt
2007-05-21 12:47 ` Folkert van Heusden
2007-05-21 12:47 ` Folkert van Heusden
2007-05-21 13:58 ` Andrea Righi
2007-05-21 13:58 ` Andrea Righi
2007-05-21 18:59 ` Folkert van Heusden
2007-05-21 18:59 ` Folkert van Heusden
2007-05-21 22:15 ` Andrea Righi
2007-05-21 22:15 ` Andrea Righi
2007-05-23 18:00 ` Satyam Sharma
2007-05-23 18:00 ` Satyam Sharma
2007-05-23 18:45 ` Folkert van Heusden
2007-05-23 18:45 ` Folkert van Heusden
2007-06-10 19:53 ` Folkert van Heusden
2007-06-10 19:53 ` Folkert van Heusden
2007-06-10 20:06 ` Jiri Kosina
2007-06-10 20:06 ` Jiri Kosina
2007-06-10 20:37 ` Jan Engelhardt
2007-06-10 20:37 ` Jan Engelhardt
2007-05-18 7:50 ` Andrea Righi
2007-05-18 7:50 ` Andrea Righi
2007-05-18 9:16 ` Robin Holt
2007-05-18 9:16 ` Robin Holt
2007-05-18 15:55 ` Andrea Righi
2007-05-18 15:55 ` Andrea Righi
2007-05-18 16:05 ` Andrea Righi
2007-05-18 16:05 ` Andrea Righi
2007-05-18 16:34 ` Bernd Eckenfels
2007-05-19 10:33 ` [PATCH 1/2] limit print_fatal_signal() rate (was: [RFC] log out-of-virtual-memory events) Andrea Righi
2007-05-19 10:33 ` Andrea Righi
2007-05-21 3:31 ` Andrew Morton
2007-05-21 3:31 ` Andrew Morton
2007-05-21 10:44 ` Andrea Righi [this message]
2007-05-21 10:44 ` [PATCH 1/2] limit print_fatal_signal() rate Andrea Righi
2007-05-24 7:58 ` [PATCH 1/2] limit print_fatal_signal() rate (was: [RFC] log out-of-virtual-memory events) Ingo Molnar
2007-05-24 7:58 ` Ingo Molnar
2007-05-24 8:15 ` Andrew Morton
2007-05-24 8:15 ` Andrew Morton
2007-05-24 9:55 ` Ingo Molnar
2007-05-24 9:55 ` Ingo Molnar
2007-05-24 16:23 ` Andrew Morton
2007-05-24 16:23 ` Andrew Morton
2007-05-24 8:50 ` [PATCH 1/2] limit print_fatal_signal() rate Andrea Righi
2007-05-24 8:50 ` Andrea Righi
2007-05-24 9:58 ` Ingo Molnar
2007-05-24 9:58 ` Ingo Molnar
2007-05-24 9:57 ` [PATCH 1/2] limit print_fatal_signal() rate (was: [RFC] log out-of-virtual-memory events) Ingo Molnar
2007-05-24 9:57 ` Ingo Molnar
2007-05-18 16:36 ` [RFC] log out-of-virtual-memory events Bernd Eckenfels
2007-05-19 10:34 ` [PATCH 2/2] log out-of-virtual-memory events (was: [RFC] log out-of-virtual-memory events) Andrea Righi
2007-05-19 10:34 ` Andrea Righi
2007-05-21 3:32 ` Andrew Morton
2007-05-21 3:32 ` Andrew Morton
2007-05-21 10:48 ` [PATCH 2/2] log out-of-virtual-memory events Andrea Righi
2007-05-21 10:48 ` Andrea Righi
2007-05-20 0:15 ` [RFC] " Folkert van Heusden
2007-05-20 0:15 ` Folkert van Heusden
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