Re: [PATCH v4 1/4] drm/amdgpu/userq: initialize gobj_read/write in amdgpu_userq_signal_ioctl

[Khatri, Sunil]

On 24-02-2026 02:09 pm, Christian König wrote:
On 2/24/26 09:24, Sunil Khatri wrote:
In case num_read_bo_handles or num_write_bo_handles is zero the ptrs
remain uninitialized and during free cause a fault. So to handle such
cases we better set the gobj_read and gobj_write to NULL.
Mhm, that doesn't sounds correct to me.

When count is zero drm_gem_objects_lookup() sets the resulting pointer to NULL:

int drm_gem_objects_lookup(struct drm_file *filp, void __user *bo_handles,
                            int count, struct drm_gem_object ***objs_out)
{
         struct drm_gem_object **objs;
         u32 *handles;
         int ret;

         *objs_out = NULL;

         if (!count)
                 return 0;


But could be that this was only added by Srinis patch and previously we didn't 
do that correctly.

For now i see the crash due to random ptr access. ASDN does not have the 
above code and we need to fix it for now.

Regards
Sunil Khatri


Regards,
Christian.

Fixes: 3cf117572294 ("drm/amdgpu/userq: Use drm_gem_objects_lookup in 
amdgpu_userq_signal_ioctl")
Signed-off-by: Sunil Khatri <sunil.kha...@amd.com>
---
  drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
index 18e77b61b201..e53e14e3bf2d 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
@@ -465,7 +465,7 @@ int amdgpu_userq_signal_ioctl(struct drm_device *dev, void 
*data,
        const unsigned int num_read_bo_handles = args->num_bo_read_handles;
        struct amdgpu_fpriv *fpriv = filp->driver_priv;
        struct amdgpu_userq_mgr *userq_mgr = &fpriv->userq_mgr;
-       struct drm_gem_object **gobj_write, **gobj_read;
+       struct drm_gem_object **gobj_write = NULL, **gobj_read = NULL;
        u32 *syncobj_handles, num_syncobj_handles;
        struct amdgpu_userq_fence *userq_fence;
        struct amdgpu_usermode_queue *queue;