On Thu, Sep 16, 2021 at 9:50 PM Mark Langsdorf <mlangsdo@xxxxxxxxxx> 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@xxxxxxxxxx>
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
>
