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From: "Rafael J. Wysocki" <rafael@kernel.org>
To: Mark Langsdorf <mlangsdo@redhat.com>
Cc: ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
	Robert Moore <robert.moore@intel.com>
Subject: Re: [PATCH] ACPI: SPCR: check if table->serial_port.access_width is too wide
Date: Fri, 24 Sep 2021 18:10:13 +0200	[thread overview]
Message-ID: <CAJZ5v0gGena0k1ne265-+iSDRB9di24ASLuvxHHYk1R3qyz2_A@mail.gmail.com> (raw)
In-Reply-To: <20210916194957.197119-1-mlangsdo@redhat.com>

On Thu, Sep 16, 2021 at 9:50 PM Mark Langsdorf <mlangsdo@redhat.com> wrote:
>
> If table->serial_port.access_width is more than 29, it causes
> undefined behavior when ACPI_ACCESS_BIT_WIDTH shifts it to
> (1 << ((size) + 2)):
>
> [    0.000000] UBSAN: Undefined behaviour in drivers/acpi/spcr.c:114:11
> [    0.000000] shift exponent 102 is too large for 32-bit type 'int'
>
> Test that serial_port.access_width is less than 30 and set it to 6
> if it is not.
>
> Signed-off-by: Mark Langsdorf <mlangsdo@redhat.com>

This consists of a Linux part and an ACPICA part (the changes in
actypes.h).  The ACPICA part needs to be submitted to the upstream
project before applying this.

> ---
>  drivers/acpi/spcr.c    |  8 ++++++--
>  include/acpi/actypes.h | 10 ++++++++--
>  2 files changed, 14 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/acpi/spcr.c b/drivers/acpi/spcr.c
> index 134f7f60cf8102..52f17d631d24e9 100644
> --- a/drivers/acpi/spcr.c
> +++ b/drivers/acpi/spcr.c
> @@ -111,8 +111,12 @@ int __init acpi_parse_spcr(bool enable_earlycon, bool enable_console)
>                 pr_info("SPCR table version %d\n", table->header.revision);
>
>         if (table->serial_port.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
> -               switch (ACPI_ACCESS_BIT_WIDTH((
> -                       table->serial_port.access_width))) {
> +               u32 bit_width = table->serial_port.access_width;
> +               if(bit_width > ACPI_ACCESS_BIT_MAX) {
> +                       pr_err("Unacceptable wide SPCR Access Width.  Defaulting to byte size\n");
> +                       bit_width = ACPI_ACCESS_BIT_DEFAULT;
> +               }
> +               switch (ACPI_ACCESS_BIT_WIDTH((bit_width))) {
>                 default:
>                         pr_err("Unexpected SPCR Access Width.  Defaulting to byte size\n");
>                         fallthrough;
> diff --git a/include/acpi/actypes.h b/include/acpi/actypes.h
> index 92c71dfce0d5d9..cefbb7ad253e02 100644
> --- a/include/acpi/actypes.h
> +++ b/include/acpi/actypes.h
> @@ -536,8 +536,14 @@ typedef u64 acpi_integer;
>   * Can be used with access_width of struct acpi_generic_address and access_size of
>   * struct acpi_resource_generic_register.
>   */
> -#define ACPI_ACCESS_BIT_WIDTH(size)     (1 << ((size) + 2))
> -#define ACPI_ACCESS_BYTE_WIDTH(size)    (1 << ((size) - 1))
> +#define ACPI_ACCESS_BIT_SHIFT          2
> +#define ACPI_ACCESS_BYTE_SHIFT         -1
> +#define ACPI_ACCESS_BIT_MAX            (31 - ACPI_ACCESS_BIT_SHIFT)
> +#define ACPI_ACCESS_BYTE_MAX           (31 - ACPI_ACCESS_BYTE_SHIFT)
> +#define ACPI_ACCESS_BIT_DEFAULT                (8 - ACPI_ACCESS_BIT_SHIFT)
> +#define ACPI_ACCESS_BYTE_DEFAULT       (8 - ACPI_ACCESS_BYTE_SHIFT)
> +#define ACPI_ACCESS_BIT_WIDTH(size)    (1 << ((size) + ACPI_ACCESS_BIT_SHIFT))
> +#define ACPI_ACCESS_BYTE_WIDTH(size)   (1 << ((size) + ACPI_ACCESS_BYTE_SHIFT))
>
>  /*******************************************************************************
>   *
> --
> 2.26.3
>

  reply	other threads:[~2021-09-24 16:10 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-16 19:49 Mark Langsdorf
2021-09-24 16:10 ` Rafael J. Wysocki [this message]
2021-09-24 17:11   ` Mark Langsdorf

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