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From: zhong jiang <zhongjiang@huawei.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>, <akpm@linux-foundation.org>,
	<mingo@redhat.com>, <minchan@kernel.org>, <mhocko@suse.com>,
	<hpa@zytor.com>, <x86@kernel.org>, <linux-mm@kvack.org>,
	<linux-kernel@vger.kernel.org>,
	"Zhen Lei" <thunder.leizhen@huawei.com>
Subject: Re: [PATCH] futex: avoid undefined behaviour when shift exponent is negative
Date: Sat, 26 Aug 2017 10:51:35 +0800	[thread overview]
Message-ID: <59A0E237.1070501@huawei.com> (raw)
In-Reply-To: <alpine.DEB.2.20.1708252308500.2124@nanos>

On 2017/8/26 5:13, Thomas Gleixner wrote:
> On Fri, 25 Aug 2017, zhong jiang wrote:
>> From: zhong jiang <zhongjiang@huawei.com>
>> Date: Fri, 25 Aug 2017 12:05:56 +0800
>> Subject: [PATCH v2] futex: avoid undefined behaviour when shift exponent is
>>  negative
> Please do not send patches without changing the subject line so it's clear
> that there is a new patch.
  ok
>> using a shift value < 0 or > 31 will get crap as a result. because
>> it's just undefined. The issue still disturb me, so I try to fix
>> it again by excluding the especially condition.
> Which is obsolete now as this code is unified accross all architectures and
> the shift issue is addressed in the generic version of it. So all
> architectures get the same fix. See:
>
>  http://git.kernel.org/tip/30d6e0a4190d37740e9447e4e4815f06992dd8c3
  ok , I  miss the above patch.
> And no, we won't add that x86 fix before that unification hits mainline
> because that undefined behaviour is harmless as it only affects the user
> space value of the futex. IOW, the caller gets what it asked for: crap.
  Thank you for clarification.

  Regards
 zhongjiang
> Thanks,
>
> 	tglx
>
>
> .
>
 

WARNING: multiple messages have this Message-ID (diff)
From: zhong jiang <zhongjiang@huawei.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>,
	akpm@linux-foundation.org, mingo@redhat.com, minchan@kernel.org,
	mhocko@suse.com, hpa@zytor.com, x86@kernel.org,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Zhen Lei <thunder.leizhen@huawei.com>
Subject: Re: [PATCH] futex: avoid undefined behaviour when shift exponent is negative
Date: Sat, 26 Aug 2017 10:51:35 +0800	[thread overview]
Message-ID: <59A0E237.1070501@huawei.com> (raw)
In-Reply-To: <alpine.DEB.2.20.1708252308500.2124@nanos>

On 2017/8/26 5:13, Thomas Gleixner wrote:
> On Fri, 25 Aug 2017, zhong jiang wrote:
>> From: zhong jiang <zhongjiang@huawei.com>
>> Date: Fri, 25 Aug 2017 12:05:56 +0800
>> Subject: [PATCH v2] futex: avoid undefined behaviour when shift exponent is
>>  negative
> Please do not send patches without changing the subject line so it's clear
> that there is a new patch.
  ok
>> using a shift value < 0 or > 31 will get crap as a result. because
>> it's just undefined. The issue still disturb me, so I try to fix
>> it again by excluding the especially condition.
> Which is obsolete now as this code is unified accross all architectures and
> the shift issue is addressed in the generic version of it. So all
> architectures get the same fix. See:
>
>  http://git.kernel.org/tip/30d6e0a4190d37740e9447e4e4815f06992dd8c3
  ok , I  miss the above patch.
> And no, we won't add that x86 fix before that unification hits mainline
> because that undefined behaviour is harmless as it only affects the user
> space value of the futex. IOW, the caller gets what it asked for: crap.
  Thank you for clarification.

  Regards
 zhongjiang
> Thanks,
>
> 	tglx
>
>
> .
>
 

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  reply	other threads:[~2017-08-26  2:52 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-21 11:43 [PATCH] futex: avoid undefined behaviour when shift exponent is negative zhong jiang
2017-06-21 16:40 ` Ingo Molnar
2017-06-21 16:40   ` Ingo Molnar
2017-06-28  4:35   ` zhong jiang
2017-06-28  4:35     ` zhong jiang
2017-06-28 21:43     ` hpa
2017-06-28 21:43       ` hpa
2017-06-29  2:12       ` zhong jiang
2017-06-29  2:12         ` zhong jiang
2017-06-29  4:29         ` hpa
2017-06-29  4:29           ` hpa
2017-06-29  5:57           ` zhong jiang
2017-06-29  5:57             ` zhong jiang
2017-06-28 22:13     ` Thomas Gleixner
2017-06-28 22:13       ` Thomas Gleixner
2017-06-29  1:54       ` zhong jiang
2017-06-29  1:54         ` zhong jiang
2017-06-29  6:33         ` Thomas Gleixner
2017-06-29  6:33           ` Thomas Gleixner
2017-06-29  7:04           ` zhong jiang
2017-06-29  7:04             ` zhong jiang
2017-08-25  5:21       ` zhong jiang
2017-08-25  5:21         ` zhong jiang
2017-08-25 21:13         ` Thomas Gleixner
2017-08-25 21:13           ` Thomas Gleixner
2017-08-26  2:51           ` zhong jiang [this message]
2017-08-26  2:51             ` zhong jiang

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