Re: [PATCH v2] accel/amdxdna: fix NULL deref and GEM object leak in error paths

[Lizhi Hou <lizhi.hou@amd.com>]

On 8/29/26 01:56, Deniz Aydogan wrote:
> amdxdna_cmd_submit() does not set job->cmd_bo for internal driver
> commands that pass AMDXDNA_INVALID_BO_HANDLE. When such a job hits
> an error or completes normally, both the submit error path and
> amdxdna_sched_job_cleanup() call amdxdna_gem_put_obj(job->cmd_bo)
> unconditionally, dereferencing NULL.
>
> Separately, amdxdna_cmd_set_error() acquires a GEM reference via
> amdxdna_gem_get_obj() when handling a chained command, but leaks it
> when the subsequent amdxdna_gem_vmap() returns NULL.
>
> Guard all three amdxdna_gem_put_obj(job->cmd_bo) call sites with a
> NULL check and release the GEM reference on vmap failure.
>
> Fixes: 3ba13f5e7180 ("Merge tag 'devicetree-fixes-for-7.3-1'")
> Signed-off-by: Deniz Aydogan <denizaydogan1902@gmail.com>
> ---
>   drivers/accel/amdxdna/amdxdna_ctx.c | 10 +++++++---
>   1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/accel/amdxdna/amdxdna_ctx.c b/drivers/accel/amdxdna/amdxdna_ctx.c
> index 31a414c3f..a806702ec 100644
> --- a/drivers/accel/amdxdna/amdxdna_ctx.c
> +++ b/drivers/accel/amdxdna/amdxdna_ctx.c
> @@ -183,8 +183,10 @@ int amdxdna_cmd_set_error(struct amdxdna_gem_obj *abo,
>   		if (!abo)
>   			return -EINVAL;
>   		cmd = amdxdna_gem_vmap(abo);
> -		if (!cmd)
> +		if (!cmd) {
> +			amdxdna_gem_put_obj(abo);
>   			return -ENOMEM;
This is fixed by: 
https://lore.kernel.org/all/17811ffc-f33b-b3ac-865b-18138239e0dd@amd.com/
> +		}
>   	}
>   
>   	memset(cmd->data, 0xff, abo->mem.size - sizeof(*cmd));
> @@ -575,7 +577,8 @@ void amdxdna_sched_job_cleanup(struct amdxdna_sched_job *job)
>   	trace_amdxdna_debug_point(job->hwctx->name, job->seq, "job release");
>   	amdxdna_pm_suspend_put(job->hwctx->client->xdna);
>   	amdxdna_arg_bos_put(job);
> -	amdxdna_gem_put_obj(job->cmd_bo);
> +	if (job->cmd_bo)
> +		amdxdna_gem_put_obj(job->cmd_bo);

The current code will not crash because drm_gem_object_put will check 
the if the obj pointer is NULL.

And I agree it is more robuster to check job->cmd_bo. Could you remove 
the "Fixes" tag and previous leak fix?

Thanks

Lizhi

>   	dma_fence_put(job->fence);
>   	mmdrop(job->mm);
>   }
> @@ -676,7 +679,8 @@ int amdxdna_cmd_submit(struct amdxdna_client *client,
>   put_bos:
>   	amdxdna_arg_bos_put(job);
>   cmd_put:
> -	amdxdna_gem_put_obj(job->cmd_bo);
> +	if (job->cmd_bo)
> +		amdxdna_gem_put_obj(job->cmd_bo);
>   free_job:
>   	if (job->mm)
>   		mmdrop(job->mm);