Re: [PATCH] nouveau/gsp: fix NULL pointer dereference in r535 nvenc/ofs alloc

["Danilo Krummrich" <dakr@kernel.org>]

On Tue May 26, 2026 at 3:47 AM CEST, Hongling Zeng wrote:
> nvkm_gsp_rm_alloc_get() can return NULL as well as error pointers.
> The current code only checks for error pointers with IS_ERR(), which
> would lead to a NULL pointer dereference if NULL is returned.
>
> Fix by using IS_ERR_OR_NULL() instead of IS_ERR(), matching the
> pattern used in nvkm_gsp_rm_alloc().

There was a similar patch [1] a while ago for another callsite. I replied:

	Are we sure that this can ever return NULL in the first place? I know
	that nvkm_gsp_rm_alloc_get() internally checks for IS_ERR_OR_NULL(), but
	I couldn't find anything within the callchain that would actually return
	NULL.
	
	That said, I think IS_ERR_OR_NULL() checks are misleading.

Is there a real case where NULL can be returned? If not, let's remove the
IS_ERR_OR_NULL() throughout the whole chain instead.

[1] https://lore.kernel.org/lkml/20260418071412.86022-1-sunliming@linux.dev/