linux-kernel - Re: PTRACE_SYSCALL && vsyscall (Was: arch_check_bp_in

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Message-ID: <a370d0f1bac7b2cee0bd2c2eea1ce22f.squirrel@mail.sublimeip.com>
Date:	Mon, 14 Jan 2013 13:31:55 +1100
From:	u3557@...o.sublimeip.com
To:	"Oleg Nesterov" <oleg@...hat.com>
Cc:	u3557@...o.sublimeip.com, "Pedro Alves" <palves@...hat.com>,
	"Denys Vlasenko" <dvlasenk@...hat.com>,
	"Jan Kratochvil" <jan.kratochvil@...hat.com>,
	"Cyrill Gorcunov" <gorcunov@...nvz.org>,
	"Pavel Emelyanov" <xemul@...allels.com>,
	"Steven Rostedt" <rostedt@...dmis.org>,
	"Frederic Weisbecker" <fweisbec@...il.com>,
	"Ingo Molnar" <mingo@...hat.com>,
	"Peter Zijlstra" <a.p.zijlstra@...llo.nl>,
	linux-kernel@...r.kernel.org
Subject: Re: PTRACE_SYSCALL && vsyscall (Was: arch_check_bp_in_kernelspace:
 fix the range check)

Hi,

> I would not say this is a bug but let me repeat, no need to convince me.
>
> Please feel free to re-send the patch(es) I sent to maintainers. Sorry,
> I can't push these changes into Linus's tree.

So here again is the patch that I need so badly - clearly it fixes a bug
and harms nobody:

-----------------------------------------------------------------------
diff -Naur before/arch/x86/kernel/hw_breakpoint.c
after/arch/x86/kernel/hw_breakpoint.c
--- before/arch/x86/kernel/hw_breakpoint.c	2013-01-14 12:45:20.000000000
+1030
+++ after/arch/x86/kernel/hw_breakpoint.c	2013-01-14 12:46:24.000000000 +1030
@@ -200,7 +200,8 @@
 	va = info->address;
 	len = get_hbp_len(info->len);

-	return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
+	return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE) &&
+		!((va >= VSYSCALL_START) && ((va + len - 1) <= VSYSCALL_END));
 }

 int arch_bp_generic_fields(int x86_len, int x86_type,
-----------------------------------------------------------------------

Where else can I send it?
Amnon.

> On 01/10, u3557@...o.sublimeip.com wrote:
>>
>> Hi Everyone,
>>
>> > On 01/08, Pedro Alves wrote:
>> >>
>> >> On 12/04/2012 05:59 PM, Oleg Nesterov wrote:
>> >>
>> >> > But If we want to allow to trace vsyscall's, hw bp doesn't look
>> very
>> >> > nice imo. HBP_NUM = 4 and you need to setup 3 bp's to trace them
>> all.
>> >>
>> >> Irrespective of the whole syscall tracing issue, allowing HW bkpts in
>> >> the vsyscall just seems like a bug fix to me.
>> >
>> > And I never argued. I sent the patch iirc ;)
>>
>> Exactly, it is a bug and I am still waiting for it to be fixed in the
>> Linux kernel.
>
> I would not say this is a bug but let me repeat, no need to convince me.
>
> Please feel free to re-send the patch(es) I sent to maintainers. Sorry,
> I can't push these changes into Linus's tree.
>
> Oleg.
>
>

Download attachment "patch" of type "application/octet-stream" (571 bytes)