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>
---
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
