bug#79336: [PATCH] df: fix potential null pointer dereference

> On 29/08/2025 02:45, yubiao hu wrote:
>> * src/df.c (get_dev): Fix potential null pointer dereference
>> - Avoid dereferencing stat_file when both device and
>>   mount_point are NULL
>> - Handle allocation failure for cell when mount_point
>>   is NULL
>
> These are valid concerns.
> I also see potential null dereferences of device.
> The attached patch takes a different approach
> by ensuring arguments are initialized earlier.
>
> Marking this as done.
>
> Will push the attached later.

Thank you for the code optimization. I would like to highlight a
potential issue: if both mount_point and device are NULL, stat_file
still end up being NULL. This could lead to a core dump at the
`error(0, errno, "%s", quotef(stat_file));`

However, there may never be a situation where both mount_point and
device are null at the same time.