On 10/30/2024 16:06, Antonio Quartulli wrote:
Hi Mario,
On 30/10/2024 02:41, Mario Limonciello wrote:
On 10/29/2024 18:32, Antonio Quartulli wrote:
acpi_evaluate_object() may return AE_NOT_FOUND (failure), which
would result in dereferencing buffer.pointer (obj) while being NULL.
Bail out also when status is AE_NOT_FOUND with a proper error message.
This fixes 1 FORWARD_NULL issue reported by Coverity
Report: CID 1600951: Null pointer dereferences (FORWARD_NULL)
Signed-off-by: Antonio Quartulli <antonio@xxxxxxxxxxxxx>
I'm not really sure how realistic this failure is. Can you share the
full call trace that Coverity identified?
I just checked Coverity Scan and it only says:
5. Condition status, taking true branch.
6. Condition status != 5U /* (acpi_status)(5 | 0) */, taking false
branch.
The above points are related to:
if (ACPI_FAILURE(status) && status != AE_NOT_FOUND)
It doesn't show how acpi_evaluate_object() is expected to return
AE_NOT_FOUND.
This said, if you think this case is unrealistic, why do you check for
"status != AE_NOT_FOUND" at all?
At this point maybe it would make more sense to simply drop this check
and always bail out with the current error message.
Basically a patch with the following only:
- /* 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)) {
This way we don't make a fuzz for a possibly unrealistic case, while
still protecting against bugs and null-dereferences.
Yeah I think that's a good idea. Can you respin it as a v2?
Regards,
amdgpu_atif_pci_probe_handle() will check whether the handle is
available in the first place. We'll never this this far if that failed.
Because of that I don't follow how this could return AE_NOT_FOUND.
---
drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c b/drivers/gpu/
drm/amd/amdgpu/amdgpu_acpi.c
index cce85389427f..f10c3261a4ab 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
@@ -172,10 +172,13 @@ 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) {
- DRM_DEBUG_DRIVER("failed to evaluate ATIF got %s\n",
- acpi_format_exception(status));
+ /* Fail if calling the method fails */
+ if (ACPI_FAILURE(status)) {
+ if (status != AE_NOT_FOUND)
+ DRM_DEBUG_DRIVER("failed to evaluate ATIF got %s\n",
+ acpi_format_exception(status));
+ else
+ DRM_DEBUG_DRIVER("ATIF not supported\n");
kfree(obj);
return NULL;
}
