linux-kernel - Re: [PATCH v9] tpm: Map the ACPI provided event log

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Message-ID: <583ca33e-aeb3-4401-8f72-9ad1a26d895d@linux.ibm.com>
Date: Wed, 15 Jan 2025 17:03:04 -0500
From: Stefan Berger <stefanb@...ux.ibm.com>
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>,
        Reiner Sailer <sailer@...ibm.com>, Seiji Munetoh <munetoh@...ibm.com>,
        Kylene Jo Hall <kjhall@...ibm.com>, Stefan Berger <stefanb@...ibm.com>,
        Andrew Morton <akpm@...l.org>
Cc: Ard Biesheuvel <ardb@...nel.org>, stable@...r.kernel.org,
        Andy Liang <andy.liang@....com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v9] tpm: Map the ACPI provided event log



On 1/15/25 4:22 PM, 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 with kvmalloc() and devm_add_action_or_reset().

Before at it was (at least) failing when the BIOS requested an excessive 
size. Now since you don't want to limit the size of the log I suppose 
you wouldn't also want to set a size of what is excessive so that the 
driver could dev_warn() the user of an excessive-sized buffer ...

> 
> Suggested-by: Ard Biesheuvel <ardb@...nel.org>
> 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
> Signed-off-by: Jarkko Sakkinen <jarkko@...nel.org>

Reviewed-by: Stefan Berger <stefanb@...ux.ibm.com>

> ---
> v9:
> * Call devm_add_action() as the last step and execute the plain action
>    in the fallback path:
>    https://lore.kernel.org/linux-integrity/87frlzzx14.wl-tiwai@suse.de/
> v8:
> * Reduced to only to this quick fix. Let HPE reserve 16 MiB if they want
>    to. We have mapping approach backed up in lore.
> v7:
> * Use devm_add_action_or_reset().
> * Fix tags.
> v6:
> * A new patch.
> ---
>   drivers/char/tpm/eventlog/acpi.c | 15 +++++++++++++--
>   1 file changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/char/tpm/eventlog/acpi.c b/drivers/char/tpm/eventlog/acpi.c
> index 69533d0bfb51..cf02ec646f46 100644
> --- a/drivers/char/tpm/eventlog/acpi.c
> +++ b/drivers/char/tpm/eventlog/acpi.c
> @@ -63,6 +63,11 @@ static bool tpm_is_tpm2_log(void *bios_event_log, u64 len)
>   	return n == 0;
>   }
>   
> +static void tpm_bios_log_free(void *data)
> +{
> +	kvfree(data);
> +}
> +
>   /* read binary bios log */
>   int tpm_read_log_acpi(struct tpm_chip *chip)
>   {
> @@ -136,7 +141,7 @@ int tpm_read_log_acpi(struct tpm_chip *chip)
>   	}
>   
>   	/* malloc EventLog space */
> -	log->bios_event_log = devm_kmalloc(&chip->dev, len, GFP_KERNEL);
> +	log->bios_event_log = kvmalloc(len, GFP_KERNEL);
 >   	if (!log->bios_event_log)>   		return -ENOMEM;
>   
> @@ -161,10 +166,16 @@ int tpm_read_log_acpi(struct tpm_chip *chip)
>   		goto err;
>   	}
>   
> +	ret = devm_add_action(&chip->dev, tpm_bios_log_free, log->bios_event_log);
> +	if (ret) {
> +		log->bios_event_log = NULL;
> +		goto err;
> +	}
> +
>   	return format;
>   
>   err:
> -	devm_kfree(&chip->dev, log->bios_event_log);
> +	tpm_bios_log_free(log->bios_event_log);
>   	log->bios_event_log = NULL;
>   	return ret;
>   }