From: "Madhavan T. Venkataraman" <madvenka@linux.microsoft.com>
To: Mark Brown <broonie@kernel.org>
Cc: jpoimboe@redhat.com, mark.rutland@arm.com, jthierry@redhat.com,
catalin.marinas@arm.com, will@kernel.org, jmorris@namei.org,
pasha.tatashin@soleen.com, linux-arm-kernel@lists.infradead.org,
live-patching@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH v3 2/4] arm64: Check the return PC against unreliable code sections
Date: Thu, 6 May 2021 10:21:37 -0500 [thread overview]
Message-ID: <67969f7f-1c2d-c287-dbdb-4ce21bd8ef23@linux.microsoft.com> (raw)
In-Reply-To: <20210506134542.GD4642@sirena.org.uk>
On 5/6/21 8:45 AM, Mark Brown wrote:
> On Wed, May 05, 2021 at 01:48:21PM -0500, Madhavan T. Venkataraman wrote:
>> On 5/5/21 11:46 AM, Mark Brown wrote:
>
>>> I think that works even if it's hard to love the goto, might want some
>>> defensiveness to ensure we can't somehow end up in an infinite loop with
>>> a sufficiently badly formed stack.
>
>> I could do something like this:
>
>> unwind_frame()
>> {
>> int i;
>> ...
>>
>> for (i = 0; i < MAX_CHECKS; i++) {
>> if (!check_frame(tsk, frame))
>> break;
>> }
>
> I think that could work, yes. Have to see the actual code (and other
> people's opinions!).
>
>> If this is acceptable, then the only question is - what should be the value of
>> MAX_CHECKS (I will rename it to something more appropriate)?
>
> I'd expect something like 10 to be way more than we'd ever need, or we
> could define it down to the 2 checks we expect to be possible ATM to be
> conservative. I'm tempted to be permissive if we have sufficient other
> checks but I'm not 100% sure on that.
>
OK. I will implement these changes for version 4 and send it out so this
whole thing can be reviewed again with the actual changes in front of us.
Madhavan
next prev parent reply other threads:[~2021-05-06 15:21 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <65cf4dfbc439b010b50a0c46ec500432acde86d6>
2021-05-03 17:36 ` [RFC PATCH v3 0/4] arm64: Stack trace reliability checks in the unwinder madvenka
2021-05-03 17:36 ` [RFC PATCH v3 1/4] arm64: Introduce stack " madvenka
2021-05-04 15:50 ` Mark Brown
2021-05-04 19:14 ` Madhavan T. Venkataraman
2021-05-04 21:52 ` Josh Poimboeuf
2021-05-04 23:13 ` Madhavan T. Venkataraman
2021-05-05 0:07 ` Josh Poimboeuf
2021-05-05 0:21 ` Madhavan T. Venkataraman
2021-05-03 17:36 ` [RFC PATCH v3 2/4] arm64: Check the return PC against unreliable code sections madvenka
2021-05-04 16:05 ` Mark Brown
2021-05-04 19:03 ` Madhavan T. Venkataraman
2021-05-04 19:32 ` Madhavan T. Venkataraman
2021-05-05 16:46 ` Mark Brown
2021-05-05 18:48 ` Madhavan T. Venkataraman
2021-05-05 18:50 ` Madhavan T. Venkataraman
2021-05-06 13:45 ` Mark Brown
2021-05-06 15:21 ` Madhavan T. Venkataraman [this message]
2021-05-05 16:34 ` Mark Brown
2021-05-05 17:51 ` Madhavan T. Venkataraman
2021-05-05 19:30 ` Ard Biesheuvel
2021-05-05 20:00 ` Madhavan T. Venkataraman
2021-05-03 17:36 ` [RFC PATCH v3 3/4] arm64: Handle miscellaneous functions in .text and .init.text madvenka
2021-05-06 14:12 ` Mark Brown
2021-05-06 15:30 ` Madhavan T. Venkataraman
2021-05-06 15:32 ` Madhavan T. Venkataraman
2021-05-06 15:44 ` Mark Brown
2021-05-06 15:56 ` Madhavan T. Venkataraman
2021-05-06 15:37 ` Mark Brown
2021-05-06 15:57 ` Madhavan T. Venkataraman
2021-05-03 17:36 ` [RFC PATCH v3 4/4] arm64: Handle funtion graph tracer better in the unwinder madvenka
2021-05-06 14:43 ` Mark Brown
2021-05-06 15:20 ` Madhavan T. Venkataraman
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