[ 3.5.y.z extended stable ] Patch "ACPICA: Fix possible buffer overflow during a field unit read" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    ACPICA: Fix possible buffer overflow during a field unit read

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From fb55247fbb398cbffffdb6b4bd8c16c8575345ef Mon Sep 17 00:00:00 2001
From: Bob Moore <robert.moore at intel.com>
Date: Wed, 8 May 2013 04:01:15 +0000
Subject: [PATCH] ACPICA: Fix possible buffer overflow during a field unit read
 operation

commit 61388f9e5d93053cf399a356414f31f9b4814c6d upstream.

Can only happen under these conditions: 1) The DSDT version is 1,
meaning integers are 32-bits.  2) The field is between 33 and 64
bits long.

It applies cleanly back to ACPICA 20100806+ (Linux v2.6.37+).

Signed-off-by: Bob Moore <robert.moore at intel.com>
Signed-off-by: Lv Zheng <lv.zheng at intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki at intel.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/acpi/acpica/exfldio.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/acpica/exfldio.c b/drivers/acpi/acpica/exfldio.c
index 149de45..af9f1f6 100644
--- a/drivers/acpi/acpica/exfldio.c
+++ b/drivers/acpi/acpica/exfldio.c
@@ -722,7 +722,19 @@ acpi_ex_extract_from_field(union acpi_operand_object *obj_desc,

 	if ((obj_desc->common_field.start_field_bit_offset == 0) &&
 	    (obj_desc->common_field.bit_length == access_bit_width)) {
-		status = acpi_ex_field_datum_io(obj_desc, 0, buffer, ACPI_READ);
+		if (buffer_length >= sizeof(u64)) {
+			status =
+			    acpi_ex_field_datum_io(obj_desc, 0, buffer,
+						   ACPI_READ);
+		} else {
+			/* Use raw_datum (u64) to handle buffers < 64 bits */
+
+			status =
+			    acpi_ex_field_datum_io(obj_desc, 0, &raw_datum,
+						   ACPI_READ);
+			ACPI_MEMCPY(buffer, &raw_datum, buffer_length);
+		}
+
 		return_ACPI_STATUS(status);
 	}

--
1.8.1.2