Commit ee3fe99f authored by Mark Langsdorf's avatar Mark Langsdorf Committed by Rafael J. Wysocki
Browse files

ACPI: SPCR: check if table->serial_port.access_width is too wide 



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: default avatarMark Langsdorf <mlangsdo@redhat.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent bca21755

drivers/acpi/spcr.c

+7 −2
Original line number Diff line number Diff line
@@ -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;