Re: [PATCH] drm/panthor: Fix potential memleak of vma structure

[Boris Brezillon <boris.brezillon@collabora.com>]

On Mon, 20 Oct 2025 09:59:14 +0100
Akash Goel <akash.goel@arm.com> wrote:

> This commit addresses a memleak issue of panthor_vma (or drm_gpuva)
> structure in Panthor driver, that can happen if the GPU page table
> update operation to map the pages fail.
> The issue is very unlikely to occur in practice.
> 
> Fixes: 647810ec2476 ("drm/panthor: Add the MMU/VM logical block")
> Signed-off-by: Akash Goel <akash.goel@arm.com>
> ---
>  drivers/gpu/drm/panthor/panthor_mmu.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
> index 6dec4354e378..34a86f7b58d9 100644
> --- a/drivers/gpu/drm/panthor/panthor_mmu.c
> +++ b/drivers/gpu/drm/panthor/panthor_mmu.c
> @@ -2081,8 +2081,10 @@ static int panthor_gpuva_sm_step_map(struct drm_gpuva_op *op, void *priv)
>  	ret = panthor_vm_map_pages(vm, op->map.va.addr, flags_to_prot(vma->flags),
>  				   op_ctx->map.sgt, op->map.gem.offset,
>  				   op->map.va.range);
> -	if (ret)
> +	if (ret) {
> +		kfree(vma);

Calling kfree() in this context is probably fine, but I think I'd
prefer if we were introducing a panthor_vm_op_ctx_return_vma() helper
returning the vma to the preallocated array, and letting the deferred
cleanup function free this up.

>  		return ret;
> +	}
>  
>  	/* Ref owned by the mapping now, clear the obj field so we don't release the
>  	 * pinning/obj ref behind GPUVA's back.