[patch 11/56] prevent kprobes from catching spurious page faults

Greg KH
2009-02-11T00:31:57Z

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2.6.27-stable review patch. If anyone has any objections, please let us know.
------------------

From: Masami Hiramatsu <mhiramat@redhat.com>

commit 9be260a646bf76fa418ee519afa10196b3164681 upstream.

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@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
arch/x86/mm/fault.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -607,8 +607,6 @@ 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;

@@ -638,6 +636,9 @@ 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.
@@ -645,6 +646,9 @@ 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;

#ifdef CONFIG_X86_32
/* It's safe to allow irq's after cr2 has been saved and the vmalloc