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.