[PATCH v3 2/3] KEYS: Reject @desclen values >= KEY_MAX_DESC_SIZE in key_alloc()

[Eric Biggers]

On Tue, Oct 20, 2026 at 04:00:31PM +0300, Jarkko Sakkinen wrote:
> On Tue, Oct 20, 2026 at 01:57:19PM +0300, Jarkko Sakkinen wrote:
> > > Sure, this fix is still incomplete though, as I mentioned.
> > > 
> > > Turns out Sashiko found this too; see the comment on
> > > https://sashiko.dev/#/patchset/20261020013903.1244157-1-jarkko%40kernel.org
> > 
> > I did not ignore what you said honestly but I overlooked generated
> > descriptions.
> > 
> > By comparing your v2 response and Sashiko's response and going through the
> > code this is the list that I have where similar check should be placed:
> > 
> > - key_alloc(): before quota calculation (in place)
> > - __key_create_or_update():  before assigning index_key.desc_len
> > - keyring_search(): before match_preparse
> > - request_key_and_link(): before match_preparse 
> > - request_key_rcu(): before check_cached_key()
> > 
> > Some sites might require some minor changes I just wrote the around the
> > ballpark locations.
> > 
> > Did I miss any site that you are aware of?

It looks okay to me.

> - Would it make sense to wrap strlen + check into key_is_valid_desc()?

I don't think it would be very helpful.

> - Would it make sense as a safe-guard to use strnlen(), which is capped
>   to KEY_MAX_DESC_SIZE?

Not really needed.  They are NUL-terminated strings anyway.

- Eric