Re: [PATCH net-next v1] net: devmem: NULL check netdev_nl_get_dma_dev return value

[Jakub Kicinski <kuba@kernel.org>]

On Fri, 29 Aug 2025 21:59:38 +0000 Mina Almasry wrote:
> netdev_nl_get_dma_dev can return NULL. This happens in the unlikely
> scenario that netdev->dev.parent is NULL, or all the calls to the
> ndo_queue_get_dma_dev return NULL from the driver.

I probably have Friday brain but I don't see what you mean..
In net-next net_devmem_bind_dmabuf() gets a dma_dev and returns
-EOPNOTSUPP PTR if its NULL.

> Current code doesn't NULL check the return value, so it may be passed to
> net_devmem_bind_dmabuf, which AFAICT will eventually hit
> WARN_ON(!dmabuf || !dev) in dma_buf_dynamic_attach and do a kernel
> splat. Avoid this scenario by using IS_ERR_OR_NULL in place of IS_ERR.
> 
> Found by code inspection.
> 
> Note that this was a problem even before the fixes patch, since we
> passed netdev->dev.parent to net_devmem_bind_dmabuf before NULL checking
> it anyway :( But that code got removed in the fixes patch (and retained
> the bug).

If the bug exists in net please send a fix for net, and ignore net-next.
Maintainers will cope with the merge.