[04/65] ACPICA: Fix possible buffer overflow during a field unit readoperation

[Steven Rostedt]

3.6.11.5 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Bob Moore <robert.moore@xxxxxxxxx>

[ Upstream commit 61388f9e5d93053cf399a356414f31f9b4814c6d ]

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@xxxxxxxxx>
Signed-off-by: Lv Zheng <lv.zheng@xxxxxxxxx>
Cc: 2.6.37+ <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
 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 a778415..d5d9bf0 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);
 	}
 
-- 
1.7.10.4


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