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Subject[PATCH] platform/chrome: cros_ec: honor acpi=off
Date
when acpi=off is provided in bootarg, kernel crash with

BUG: kernel NULL pointer dereference, address: 0000000000000018
RIP: 0010:acpi_ns_walk_namespace+0x57/0x280
<TASK>
? acpi_get_devices+0x140/0x140
cros_ec_lpc_init+0x25/0x100

Driver should check if ACPI is disabled before calling acpi_get_devices(),
otherwise acpi_walk_namespace() will dereference null pointer since the
acpi_gbl_root_node is not initialized.
This is a common pattern and should be fixed in ACPI framework to prevent
such crash in the future, but since many drivers are already doing explicit
check(acpi_disable) we do the same thing here.

Signed-off-by: Tong Zhang <ztong0001@gmail.com>
---
drivers/platform/chrome/cros_ec_lpc.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/platform/chrome/cros_ec_lpc.c b/drivers/platform/chrome/cros_ec_lpc.c
index d6306d2a096f..95412a55ed8d 100644
--- a/drivers/platform/chrome/cros_ec_lpc.c
+++ b/drivers/platform/chrome/cros_ec_lpc.c
@@ -550,6 +550,9 @@ static int __init cros_ec_lpc_init(void)
int ret;
acpi_status status;

+ if (acpi_disable)
+ return -ENODEV;
+
status = acpi_get_devices(ACPI_DRV_NAME, cros_ec_lpc_parse_device,
&cros_ec_lpc_acpi_device_found, NULL);
if (ACPI_FAILURE(status))
--
2.25.1
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