Re: [PATCH v2] arm: kasan: clear stale stack poison

From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: "Boy Wu (吳勃誼)" <Boy.Wu@mediatek.com>
Cc: "linus.walleij@linaro.org" <linus.walleij@linaro.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-mediatek@lists.infradead.org"
	<linux-mediatek@lists.infradead.org>,
	"andreyknvl@gmail.com" <andreyknvl@gmail.com>,
	"dvyukov@google.com" <dvyukov@google.com>,
	"kasan-dev@googlegroups.com" <kasan-dev@googlegroups.com>,
	"Iverlin Wang (王苳霖)" <Iverlin.Wang@mediatek.com>,
	"mark.rutland@arm.com" <mark.rutland@arm.com>,
	"Light Chen (陳昱光)" <Light.Chen@mediatek.com>,
	"ryabinin.a.a@gmail.com" <ryabinin.a.a@gmail.com>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"glider@google.com" <glider@google.com>,
	"matthias.bgg@gmail.com" <matthias.bgg@gmail.com>,
	"vincenzo.frascino@arm.com" <vincenzo.frascino@arm.com>,
	"angelogioacchino.delregno@collabora.com"
	<angelogioacchino.delregno@collabora.com>
Subject: Re: [PATCH v2] arm: kasan: clear stale stack poison
Date: Mon, 29 Apr 2024 13:42:35 +0100	[thread overview]
Message-ID: <Zi+Vu29rmNZ0MIFG@shell.armlinux.org.uk> (raw)
In-Reply-To: <292f9fe4bab26028aa80f63bf160e0f2b874a17c.camel@mediatek.com>

On Mon, Apr 29, 2024 at 07:51:49AM +0000, Boy Wu (吳勃誼) wrote:
> On Sun, 2024-04-28 at 15:45 +0100, Russell King (Oracle) wrote:
> >  On Fri, Apr 12, 2024 at 10:37:06AM +0200, Linus Walleij wrote:
> > > On Wed, Apr 10, 2024 at 9:31 AM boy.wu <boy.wu@mediatek.com> wrote:
> > > 
> > > > From: Boy Wu <boy.wu@mediatek.com>
> > > >
> > > > We found below OOB crash:
> > > 
> > > Thanks for digging in!
> > > 
> > > Pleas put this patch into Russell's patch tracker so he can apply
> > it:
> > > https://www.armlinux.org.uk/developer/patches/
> > 
> > Is this a bug fix? If so, having a Fixes: tag would be nice...
> > 
> 
> This is a patch for cpuidle flow when KASAN enable, that is in ARM64
> but not in ARM, so add to ARM.
> 
> The reference commits did not mention fix any commits.
> [1] commit 0d97e6d8024c ("arm64: kasan: clear stale stack poison")
> [2] commit d56a9ef84bd0 ("kasan, arm64: unpoison stack only with
> CONFIG_KASAN_STACK")

These are not suitable for use as a Fixes: tag because these commits
refer to code in another part of the tree that has nothing to do with
the BUG() dump that is contained within your commit message.

I ask again... Is this a bug fix?

Is it a regression?

Is it something that used to work that no longer works?

When did it break?

Has it always been broken?

Has it been broken since KASAN was introduced on 32-bit ARM?

I'm not applying this commit until I get *proper* answers to these
questions so that I can work out whether this needs to go in -rc
or whether it waits until the next merge window... and whether it
needs a Fixes: tag or not.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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