Re: [PATCH] kernfs: fix potential NULL dereference in mmap handler

[Greg KH]

On Tue, Apr 01, 2025 at 11:18:59PM +0800, Wentao Liang wrote:
> The kernfs_fop_mmap() invokes the '->mmap' callback without verifying its
> existence. This leads to a NULL pointer dereference when the kernfs node
> does not define the operation, resulting in an invalid memory access.

How can that happen with any in-kernel user of kernfs?  If you try to
mmap any sysfs file today does this trigger?

thanks,

greg k-h