From: Srinivasan Shanmugam <[email protected]>

[ Upstream commit cdb637d339572398821204a1142d8d615668f1e9 ]

The issue arises when the array 'adev->vcn.vcn_config' is accessed
before checking if the index 'adev->vcn.num_vcn_inst' is within the
bounds of the array.

The fix involves moving the bounds check before the array access. This
ensures that 'adev->vcn.num_vcn_inst' is within the bounds of the array
before it is used as an index.

Fixes the below:
drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c:1289 
amdgpu_discovery_reg_base_init() error: testing array offset 
'adev->vcn.num_vcn_inst' after use.

Fixes: a0ccc717c4ab ("drm/amdgpu/discovery: validate VCN and SDMA instances")
Cc: Christian König <[email protected]>
Cc: Alex Deucher <[email protected]>
Signed-off-by: Srinivasan Shanmugam <[email protected]>
Reviewed-by: Alex Deucher <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>
[ Minor conflict resolved. ]
Signed-off-by: Li hongliang <[email protected]>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c
index 9b1c4d5be61f..a1e006d238cf 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c
@@ -1128,15 +1128,15 @@ static int amdgpu_discovery_reg_base_init(struct 
amdgpu_device *adev)
                                 *     0b10 : encode is disabled
                                 *     0b01 : decode is disabled
                                 */
-                               adev->vcn.vcn_config[adev->vcn.num_vcn_inst] =
-                                       ip->revision & 0xc0;
-                               ip->revision &= ~0xc0;
-                               if (adev->vcn.num_vcn_inst < 
AMDGPU_MAX_VCN_INSTANCES)
+                               if (adev->vcn.num_vcn_inst < 
AMDGPU_MAX_VCN_INSTANCES) {
+                                       
adev->vcn.vcn_config[adev->vcn.num_vcn_inst] =
+                                               ip->revision & 0xc0;
                                        adev->vcn.num_vcn_inst++;
-                               else
+                               } else
                                        dev_err(adev->dev, "Too many VCN 
instances: %d vs %d\n",
                                                adev->vcn.num_vcn_inst + 1,
                                                AMDGPU_MAX_VCN_INSTANCES);
+                               ip->revision &= ~0xc0;
                        }
                        if (le16_to_cpu(ip->hw_id) == SDMA0_HWID ||
                            le16_to_cpu(ip->hw_id) == SDMA1_HWID ||
-- 
2.34.1


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