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Message-ID: <d4f9861effd64c155f93cc712d2c7660b1cf2e4a.camel@sipsolutions.net>
Subject: Re: [PATCH] arch/x86/um: Disable UBSAN sanitization
From: Johannes Berg <johannes@sipsolutions.net>
To: Roberto Sassu <roberto.sassu@huaweicloud.com>, richard@nod.at, 
	anton.ivanov@cambridgegreys.com, tglx@linutronix.de, mingo@redhat.com, 
	bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com
Cc: x86@kernel.org, linux-um@lists.infradead.org,
 linux-kernel@vger.kernel.org,  zohar@linux.ibm.com,
 linux-integrity@vger.kernel.org, Roberto Sassu <roberto.sassu@huawei.com>
Date: Mon, 13 May 2024 15:08:30 +0200
In-Reply-To: <dba181a54e76ba2916ecd4747f76e40e6fbbb757.camel@huaweicloud.com>
References: <20240513122754.1282833-1-roberto.sassu@huaweicloud.com>
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	 <f88384a305b90708db3b30012f9edf09690dc5ee.camel@sipsolutions.net>
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On Mon, 2024-05-13 at 14:58 +0200, Roberto Sassu wrote:
> On Mon, 2024-05-13 at 14:52 +0200, Johannes Berg wrote:
> > On Mon, 2024-05-13 at 14:42 +0200, Roberto Sassu wrote:
> > > On Mon, 2024-05-13 at 14:29 +0200, Johannes Berg wrote:
> > > > On Mon, 2024-05-13 at 14:27 +0200, Roberto Sassu wrote:
> > > > > From: Roberto Sassu <roberto.sassu@huawei.com>
> > > > >=20
> > > > > Disable UBSAN sanitization on UML, since UML does not support it.
> > > > >=20
> > > >=20
> > > > Luckily, that isn't actually true, nor does it actually do this at =
all.
> > > > Please fix the commit message.
> > >=20
> > > Thanks, I was actually wondering. I based that statement based on
> > > ARCH_HAS_UBSAN=3Dn.
> > >=20
> > > Any other solution would be ok.
> >=20
> > Not sure I get it. What you're doing in the patch is perfectly fine and
> > almost certainly required, but you're definitely not disabling UBSAN on
> > ARCH=3Dum as you described in the commit message?
>=20
> Ok, I guess the right word is instrumentation (got it from commit
> d4be85d068b44). And the reason is that the vDSO is executing in user
> space. Will fix it.

No, UBSAN is fine, but you're only disabling it for the vDSO :) The
commit message doesn't even mention the vDSO though.

johannes