[PATCH] drm/nouveau/gsp: fix potential leak of memory used during acpi init

[Philipp Stanner]

On Tue, 2025-06-17 at 14:00 +1000, Ben Skeggs wrote:
> If any of the ACPI calls fail, memory allocated for the input buffer
> would be leaked.  Fix failure paths to free allocated memory.
> 
> Also add checks to ensure the allocations succeeded in the first
> place.
> 
> Reported-by: Danilo Krummrich <dakr at kernel.org>
> Fixes: 176fdcbddfd2 ("drm/nouveau/gsp/r535: add support for booting
> GSP-RM")

Needs to +Cc the stable kernel

But, see below


> Signed-off-by: Ben Skeggs <bskeggs at nvidia.com>
> ---
>  .../drm/nouveau/nvkm/subdev/gsp/rm/r535/gsp.c | 20 +++++++++++++----
> --
>  1 file changed, 14 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/gsp.c
> b/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/gsp.c
> index baf42339f93e..b098a7555fde 100644
> --- a/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/gsp.c
> +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/gsp.c

This seems to be based on a code move that is not yet in mainline.

Therefore, backporting the bugfix to stable seems difficult. Since that
code move is already in drm-misc-next, it would seem that it can only
be solved with two distinct patches for stable and for -next.

But this needs to be judged by a maintainer.

> @@ -719,7 +719,6 @@ r535_gsp_acpi_caps(acpi_handle handle,
> CAPS_METHOD_DATA *caps)
>  	union acpi_object argv4 = {
>  		.buffer.type    = ACPI_TYPE_BUFFER,
>  		.buffer.length  = 4,
> -		.buffer.pointer = kmalloc(argv4.buffer.length,
> GFP_KERNEL),
>  	}, *obj;
>  
>  	caps->status = 0xffff;
> @@ -727,17 +726,22 @@ r535_gsp_acpi_caps(acpi_handle handle,
> CAPS_METHOD_DATA *caps)
>  	if (!acpi_check_dsm(handle, &NVOP_DSM_GUID, NVOP_DSM_REV,
> BIT_ULL(0x1a)))
>  		return;
>  
> +	argv4.buffer.pointer = kmalloc(argv4.buffer.length,
> GFP_KERNEL);
> +	if (!argv4.buffer.pointer)
> +		return;
> +

This could be done immediately after the creation of argv4. That way
it's more difficult to have the leak again if something is inserted
later on.

>  	obj = acpi_evaluate_dsm(handle, &NVOP_DSM_GUID,
> NVOP_DSM_REV, 0x1a, &argv4);
>  	if (!obj)
> -		return;
> +		goto done;
>  
>  	if (WARN_ON(obj->type != ACPI_TYPE_BUFFER) ||
>  	    WARN_ON(obj->buffer.length != 4))
> -		return;
> +		goto done;
>  
>  	caps->status = 0;
>  	caps->optimusCaps = *(u32 *)obj->buffer.pointer;
>  
> +done:
>  	ACPI_FREE(obj);
>  
>  	kfree(argv4.buffer.pointer);
> @@ -754,24 +758,28 @@ r535_gsp_acpi_jt(acpi_handle handle,
> JT_METHOD_DATA *jt)
>  	union acpi_object argv4 = {
>  		.buffer.type    = ACPI_TYPE_BUFFER,
>  		.buffer.length  = sizeof(caps),
> -		.buffer.pointer = kmalloc(argv4.buffer.length,
> GFP_KERNEL),
>  	}, *obj;
>  
>  	jt->status = 0xffff;
>  
> +	argv4.buffer.pointer = kmalloc(argv4.buffer.length,
> GFP_KERNEL);
> +	if (!argv4.buffer.pointer)
> +		return;
> +
>  	obj = acpi_evaluate_dsm(handle, &JT_DSM_GUID, JT_DSM_REV,
> 0x1, &argv4);
>  	if (!obj)
> -		return;
> +		goto done;
>  
>  	if (WARN_ON(obj->type != ACPI_TYPE_BUFFER) ||
>  	    WARN_ON(obj->buffer.length != 4))
> -		return;
> +		goto done;
>  
>  	jt->status = 0;
>  	jt->jtCaps = *(u32 *)obj->buffer.pointer;
>  	jt->jtRevId = (jt->jtCaps & 0xfff00000) >> 20;
>  	jt->bSBIOSCaps = 0;
>  
> +done:

'done' seems like a bad name considering that the operations are
aborted with a WARN_ON above. Better 'abort' or sth like that.


P.

>  	ACPI_FREE(obj);
>  
>  	kfree(argv4.buffer.pointer);