diff mbox series

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

Message ID 20210916194957.197119-1-mlangsdo@redhat.com
State New
Headers show
Series ACPI: SPCR: check if table->serial_port.access_width is too wide | expand

Commit Message

Mark Langsdorf Sept. 16, 2021, 7:49 p.m. UTC
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@redhat.com>
---
 drivers/acpi/spcr.c    |  8 ++++++--
 include/acpi/actypes.h | 10 ++++++++--
 2 files changed, 14 insertions(+), 4 deletions(-)

Comments

Rafael J. Wysocki Sept. 24, 2021, 4:10 p.m. UTC | #1
On Thu, Sep 16, 2021 at 9:50 PM Mark Langsdorf <mlangsdo@redhat.com> 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'

>

> 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@redhat.com>


This consists of a Linux part and an ACPICA part (the changes in
actypes.h).  The ACPICA part needs to be submitted to the upstream
project before applying this.

> ---

>  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

>
Mark Langsdorf Sept. 24, 2021, 5:11 p.m. UTC | #2
On 9/24/21 11:10 AM, Rafael J. Wysocki wrote:
> On Thu, Sep 16, 2021 at 9:50 PM Mark Langsdorf <mlangsdo@redhat.com> 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'

>>

>> Test that serial_port.access_width is less than 30 and set it to 6

>> if it is not.

>>

>> This consists of a Linux part and an ACPICA part (the changes in

>> actypes.h).  The ACPICA part needs to be submitted to the upstream

>> project before applying this.


Thanks, I wasn't sure of the procedure. I'll get the ACPICA part 
accepted and come back with the rest.

--Mark Langsdorf
diff mbox series

Patch

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))
 
 /*******************************************************************************
  *