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Subject[16/94] ACPICA: Fix possible buffer overflow during a field unit read operation
3.2.46-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Bob Moore <robert.moore@intel.com>

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@intel.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/acpi/acpica/exfldio.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)

--- a/drivers/acpi/acpica/exfldio.c
+++ b/drivers/acpi/acpica/exfldio.c
@@ -702,7 +702,19 @@ acpi_ex_extract_from_field(union acpi_op

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);
}



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