On Wed, Jan 5, 2022 at 6:47 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'
>
> Use the new ACPI_ACCESS_ defines to 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>
> ---
> drivers/acpi/spcr.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/acpi/spcr.c b/drivers/acpi/spcr.c
> index 25c2d0be953e..d589543875b8 100644
> --- a/drivers/acpi/spcr.c
> +++ b/drivers/acpi/spcr.c
> @@ -107,8 +107,13 @@ 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;
> --
Applied as 5.17-rc material, thanks!
