Am 2022-04-04 um 18:21 schrieb Grigory Vasilyev:
In the amdgpu_amdkfd_get_xgmi_bandwidth_mbytes function,
the peer_adev pointer can be NULL and is passed to amdgpu_xgmi_get_num_links.
In amdgpu_xgmi_get_num_links, peer_adev pointer is dereferenced
without any checks: peer_adev->gmc.xgmi.node_id .
What's worse, peer_adev is uninitialized with an undefined value if src
is NULL. So that code was definitely bogus.
However, I think your patch will result in incorrect results. Currently
amdgpu_amdkfd_get_xgmi_bandwidth is always called with is_min=true if
src==NULL, and with is_min=false if src!=NULL. The intention is, that we
assume a single XGMI link in the case that src==NULL. That means the
is_min parameter is redundant. What we should do instead is, assume that
num_links==1 if src==NULL, and drop the is_min parameter.
That would keep things working the way they do now, and prevent
potential problems in the future.
Regards,
Felix
Signed-off-by: Grigory Vasilyev <h0tc0d3@xxxxxxxxx>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
index be1a55f8b8c5..1a1006b18016 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
@@ -541,11 +541,10 @@ int amdgpu_amdkfd_get_xgmi_bandwidth_mbytes(struct amdgpu_device *dst,
struct amdgpu_device *adev = dst, *peer_adev;
int num_links;
- if (adev->asic_type != CHIP_ALDEBARAN)
+ if (!src || adev->asic_type != CHIP_ALDEBARAN)
return 0;
- if (src)
- peer_adev = src;
+ peer_adev = src;
/* num links returns 0 for indirect peers since indirect route is unknown. */
num_links = is_min ? 1 : amdgpu_xgmi_get_num_links(adev, peer_adev);
