From ee3fe99ff0a27108ac38d9766ac0e92f5ec35692 Mon Sep 17 00:00:00 2001 From: Mark Langsdorf Date: Wed, 5 Jan 2022 11:47:14 -0600 Subject: 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: Mark Langsdorf Signed-off-by: Rafael J. Wysocki --- drivers/acpi/spcr.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) (limited to 'drivers/acpi/spcr.c') 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; -- cgit v1.2.3