On 6/6/20 11:24 AM, Julia Lawall wrote:
>
>
> On Sat, 30 May 2020, Denis Efremov wrote:
>
>> Match GFP_USER allocations with memdup_user.cocci rule.
>> Commit 6c2c97a24f09 ("memdup_user(): switch to GFP_USER") switched
>> memdup_user() from GFP_KERNEL to GFP_USER. In most cases it is still
>> a good idea to use memdup_user() for GFP_KERNEL allocations. The
>> motivation behind altering memdup_user() to GFP_USER is here:
>> https://lkml.org/lkml/2018/1/6/333
>
> Should the rule somehow document the cases in which memdup_user should now
> not be used?
As for now, I can't provide a counterexample. GPF_USER is more permissive than
GFP_KERNEL. It's completely ok to use GPF_USER with copy_from_user. Given that
memdup_user() was "silently" switched to GPF_USER from GPF_KERNEL with no
callside
fixes, I think it's ok to recommend to use memdup_user for GPF_KERNEL matches
with
no additional restrictions.
Thanks,
Denis
