drm/amdgpu: prevent NULL pointer dereference if ATIF is not supported

acpi_evaluate_object() may return AE_NOT_FOUND (failure), which
would result in dereferencing buffer.pointer (obj) while being NULL.

Although this case may be unrealistic for the current code, it is
still better to protect against possible bugs.

Bail out also when status is AE_NOT_FOUND.

This fixes 1 FORWARD_NULL issue reported by Coverity
Report: CID 1600951:  Null pointer dereferences  (FORWARD_NULL)

Signed-off-by: Antonio Quartulli <antonio@mandelbit.com>
Fixes: c9b7c809b8 ("drm/amd: Guard against bad data for ATIF ACPI method")
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://lore.kernel.org/r/20241031152848.4716-1-antonio@mandelbit.com
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 91c9e221fe)
Cc: stable@vger.kernel.org
This commit is contained in:
Antonio Quartulli 2024-10-31 16:28:48 +01:00 committed by Alex Deucher
parent 694c79769c
commit a6dd15981c

View File

@ -172,8 +172,8 @@ static union acpi_object *amdgpu_atif_call(struct amdgpu_atif *atif,
&buffer);
obj = (union acpi_object *)buffer.pointer;
/* Fail if calling the method fails and ATIF is supported */
if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
/* Fail if calling the method fails */
if (ACPI_FAILURE(status)) {
DRM_DEBUG_DRIVER("failed to evaluate ATIF got %s\n",
acpi_format_exception(status));
kfree(obj);