linux-kernel - Re: [PATCH v5 4/6] kselftest/arm64/mte: preparation for mtefar test

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <6b13e414-9377-4806-abd5-fdebda6c14f2@sirena.org.uk>
Date: Tue, 10 Jun 2025 16:21:39 +0100
From: Mark Brown <broonie@...nel.org>
To: Yeoreum Yun <yeoreum.yun@....com>
Cc: catalin.marinas@....com, pcc@...gle.com, will@...nel.org,
	anshuman.khandual@....com, joey.gouly@....com,
	yury.khrustalev@....com, maz@...nel.org, oliver.upton@...ux.dev,
	frederic@...nel.org, shmeerali.kolothum.thodi@...wei.com,
	akpm@...ux-foundation.org, surenb@...gle.com,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-doc@...r.kernel.org
Subject: Re: [PATCH v5 4/6] kselftest/arm64/mte: preparation for mtefar test

On Tue, Jun 10, 2025 at 04:01:42PM +0100, Yeoreum Yun wrote:
> If FEAT_MTE_TAGGED_FAR (Armv8.9) is supported, bits 63:60 of the fault address
> are preserved in response to synchronous tag check faults (SEGV_MTESERR).
> 
> This patch is preparation for testing FEAT_MTE_TAGGED_FAR.
> It shouldn't change the test result.

I'm not clear from the above what the change is intended to do (ie, how
does it prepare for testing FEAT_MTE_TAGGED_FAR).  I think this could
usefully be split out into multiple commits (eg, adding logging of the
additional si_ fields separately, or splitting the renaming MT_CLEAR_TAG
to MT_CLEAR_TAGS), it's kind of hard to review as is.

> @@ -45,13 +64,18 @@ void mte_default_handler(int signum, siginfo_t *si, void *uc)
>  		}
>  		/* Compare the context for precise error */
>  		else if (si->si_code == SEGV_MTESERR) {
> +		 	if ((!mtefar_support && si_atag) || (si_atag != MT_FETCH_ATAG(cur_mte_cxt.trig_addr))) {
> +			  ksft_print_msg("Invalid MTE synchronous exception caught for address tag! si_tag=%x, si_atag: %x\n", si_tag, si_atag);
> +			  exit(1);
> +			}

We should really exit with a kselftest error rather than just a number,
though I see this is just copying the existing style for the file so
*shrug*.

Download attachment "signature.asc" of type "application/pgp-signature" (489 bytes)