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authorAlexey Starikovskiy <astarikovskiy@suse.de>2010-04-16 15:36:40 -0400
committerGreg Kroah-Hartman <gregkh@suse.de>2010-04-26 07:41:34 -0700
commitea50da76fac43bf45365862110d3c19247411896 (patch)
treea13dbf25091695de28517e5389b710b2ca04f50c /drivers/acpi
parenta7fcc269cf6c6a531067a62716a661f4482d726a (diff)
ACPI: EC: Limit burst to 64 bits
commit 2060c44576c79086ff24718878d7edaa7384a985 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>
Diffstat (limited to 'drivers/acpi')
-rw-r--r--drivers/acpi/acpica/exprep.c17
1 files changed, 11 insertions, 6 deletions
diff --git a/drivers/acpi/acpica/exprep.c b/drivers/acpi/acpica/exprep.c
index c02d543a2601..83b62521d8d3 100644
--- a/drivers/acpi/acpica/exprep.c
+++ b/drivers/acpi/acpica/exprep.c
@@ -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,