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Message-ID: <498B6457.20302@redhat.com>
Date: Thu, 05 Feb 2009 17:12:39 -0500
From: Masami Hiramatsu <mhiramat@...hat.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Greg KH <greg@...ah.com>
CC: Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
Nick Piggin <npiggin@...e.de>,
LKML <linux-kernel@...r.kernel.org>,
Ananth N Mavinakayanahalli <ananth@...ibm.com>,
Jim Keniston <jkenisto@...ibm.com>,
systemtap-ml <systemtap@...rces.redhat.com>,
"Frank Ch. Eigler" <fche@...hat.com>
Subject: [BUGFIX][PATCH -rc/-mm] prevent kprobes from catching spurious page
faults
Prevent kprobes from catching spurious faults which will cause infinite
recursive page-fault and memory corruption by stack overflow.
Signed-off-by: Masami Hiramatsu <mhiramat@...hat.com>
---
This patch solves memory corruption bug which I reported last week.
http://lkml.org/lkml/2009/1/27/428
Since 2.6.28 kernel also has same bug, I think it should be applied
to 2.6.28.y too.
Thanks,
arch/x86/mm/fault.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
Index: linux-2.6/arch/x86/mm/fault.c
===================================================================
--- linux-2.6.orig/arch/x86/mm/fault.c
+++ linux-2.6/arch/x86/mm/fault.c
@@ -603,8 +603,6 @@ void __kprobes do_page_fault(struct pt_r
si_code = SEGV_MAPERR;
- if (notify_page_fault(regs))
- return;
if (unlikely(kmmio_fault(regs, address)))
return;
@@ -634,6 +632,9 @@ void __kprobes do_page_fault(struct pt_r
if (spurious_fault(address, error_code))
return;
+ /* kprobes don't want to hook the spurious faults. */
+ if (notify_page_fault(regs))
+ return;
/*
* Don't take the mm semaphore here. If we fixup a prefetch
* fault we could otherwise deadlock.
@@ -641,6 +642,9 @@ void __kprobes do_page_fault(struct pt_r
goto bad_area_nosemaphore;
}
+ /* kprobes don't want to hook the spurious faults. */
+ if (notify_page_fault(regs))
+ return;
/*
* It's safe to allow irq's after cr2 has been saved and the
--
Masami Hiramatsu
Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division
e-mail: mhiramat@...hat.com
--
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