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

[Eric Biggers]

On Tue, Oct 20, 2026 at 04:47:43AM +0300, Jarkko Sakkinen wrote:
> On Tue, Oct 20, 2026 at 04:38:56AM +0300, Jarkko Sakkinen wrote:
> > @desclen in key_alloc() is saved to the 16-bit wide desc_len field in
> > struct keyring_index_key.
> > 
> > Reject @desclen values at or above KEY_MAX_DESC_SIZE with -EINVAL in order
> > to match the userspace limit. The constraints inherits from the one byte
> > required for the NULL character.
> > 
> > Cc: stable at vger.kernel.org
> > Assisted-by: LLM
> > Fixes: f771fde82051 ("keys: Simplify key description management")
> > Reviewed-by: David Howells <dhowells at redhat.com>
> > Signed-off-by: Jarkko Sakkinen <jarkko at kernel.org>
> 
> This is now the only one, which does not have keyutils script in the
> commit message so in that sense I think these fixes look pretty good.

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

- Eric