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;
--
2.26.3
