linux-kernel - Re: [PATCH v5] tpm: Map the ACPI provided event log

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Message-Id: <D6JN3SL6SY8T.1VYULNCNNAHGJ@kernel.org>
Date: Tue, 24 Dec 2024 06:18:42 +0200
From: "Jarkko Sakkinen" <jarkko@...nel.org>
To: "Jarkko Sakkinen" <jarkko@...nel.org>,
 <linux-integrity@...r.kernel.org>, "Peter Huewe" <peterhuewe@....de>,
 "Jason Gunthorpe" <jgg@...pe.ca>, "Colin Ian King"
 <colin.i.king@...il.com>, "Joe Hattori" <joe@...is.s.u-tokyo.ac.jp>, "James
 Bottomley" <James.Bottomley@...senPartnership.com>, "Stefan Berger"
 <stefanb@...ux.ibm.com>, "Ard Biesheuvel" <ardb@...nel.org>, "Mimi Zohar"
 <zohar@...ux.ibm.com>, "Al Viro" <viro@...iv.linux.org.uk>, "Kylene Jo
 Hall" <kjhall@...ibm.com>, "Reiner Sailer" <sailer@...ibm.com>, "Seiji
 Munetoh" <munetoh@...ibm.com>, "Andrew Morton" <akpm@...l.org>
Cc: <stable@...r.kernel.org>, "Andy Liang" <andy.liang@....com>, "Matthew
 Garrett" <mjg59@...f.ucam.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5] tpm: Map the ACPI provided event log

On Tue Dec 24, 2024 at 6:03 AM EET, Jarkko Sakkinen wrote:
> The following failure was reported:
>
> [   10.693310][    T1] tpm_tis STM0925:00: 2.0 TPM (device-id 0x3, rev-id 0)
> [   10.848132][    T1] ------------[ cut here ]------------
> [   10.853559][    T1] WARNING: CPU: 59 PID: 1 at mm/page_alloc.c:4727 __alloc_pages_noprof+0x2ca/0x330
> [   10.862827][    T1] Modules linked in:
> [   10.866671][    T1] CPU: 59 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.12.0-lp155.2.g52785e2-default #1 openSUSE Tumbleweed (unreleased) 588cd98293a7c9eba9013378d807364c088c9375
> [   10.882741][    T1] Hardware name: HPE ProLiant DL320 Gen12/ProLiant DL320 Gen12, BIOS 1.20 10/28/2024
> [   10.892170][    T1] RIP: 0010:__alloc_pages_noprof+0x2ca/0x330
> [   10.898103][    T1] Code: 24 08 e9 4a fe ff ff e8 34 36 fa ff e9 88 fe ff ff 83 fe 0a 0f 86 b3 fd ff ff 80 3d 01 e7 ce 01 00 75 09 c6 05 f8 e6 ce 01 01 <0f> 0b 45 31 ff e9 e5 fe ff ff f7 c2 00 00 08 00 75 42 89 d9 80 e1
> [   10.917750][    T1] RSP: 0000:ffffb7cf40077980 EFLAGS: 00010246
> [   10.923777][    T1] RAX: 0000000000000000 RBX: 0000000000040cc0 RCX: 0000000000000000
> [   10.931727][    T1] RDX: 0000000000000000 RSI: 000000000000000c RDI: 0000000000040cc0
>
> Above shows that ACPI pointed a 16 MiB buffer for the log events because
> RSI maps to the 'order' parameter of __alloc_pages_noprof(). Address the
> bug by mapping the region when needed instead of copying.
>
> Cc: stable@...r.kernel.org # v2.6.16+
> Fixes: 55a82ab3181b ("[PATCH] tpm: add bios measurement log")
> Reported-by: Andy Liang <andy.liang@....com>
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219495
> Suggested-by: Matthew Garrett <mjg59@...f.ucam.org>
> Tested-by: Andy Liang <andy.liang@....com>
> Signed-off-by: Jarkko Sakkinen <jarkko@...nel.org>

Doing some weird truncate here would be pointless even if it is "too
large". It's HPE's problem, not ours. The onnly piece of code where the
fix makes any mentionable changes is really acpi.c and I've tested that
quite throughly already...

In some other version of the hardware the size was BTW 8 MiB (according
to TPM2 table contents) and later on it changed to 16 MiB (according to
transcript above i.e. RSI). That is weird but I don't think we should
care.

BR, Jarkko