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ACPI: EC: Limit burst to 64 bits

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commit 2060c44576 upstream.

access_bit_width field is u8 in ACPICA, thus 256 value written to it
becomes 0, causing divide by zero later.

Proper fix would be to remove access_bit_width at all, just because
we already have access_byte_width, which is access_bit_width / 8.
Limit access width to 64 bit for now.

https://bugzilla.kernel.org/show_bug.cgi?id=15749
fixes regression caused by the fix for:
https://bugzilla.kernel.org/show_bug.cgi?id=14667

Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alexey Starikovskiy
2010-04-16 15:36:40 -04:00
committed by Greg Kroah-Hartman
parent a7fcc269cf
commit ea50da76fa
1 changed files with 11 additions and 6 deletions
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17
drivers/acpi/acpica/exprep.c
View File

@@ -471,13 +471,18 @@ acpi_status acpi_ex_prep_field_value(struct acpi_create_field_info *info)
/* allow full data read from EC address space */
if (obj_desc->field.region_obj->region.space_id ==
ACPI_ADR_SPACE_EC) {
if (obj_desc->common_field.bit_length > 8)
obj_desc->common_field.access_bit_width =
ACPI_ROUND_UP(obj_desc->common_field.
bit_length, 8);
if (obj_desc->common_field.bit_length > 8) {
unsigned width =
ACPI_ROUND_BITS_UP_TO_BYTES(
obj_desc->common_field.bit_length);
// access_bit_width is u8, don't overflow it
if (width > 8)
width = 8;
obj_desc->common_field.access_byte_width =
ACPI_DIV_8(obj_desc->common_field.
access_bit_width);
width;
obj_desc->common_field.access_bit_width =
8 * width;
}
}
ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,