Re: [PATCH] s390/cert_store: Hold the keyring->sem while invalidating keys

[Jarkko Sakkinen <jarkko@kernel.org>]

On Wed, Oct 28, 2026 at 04:34:19PM +0100, Heiko Carstens wrote:
> On Sat, Oct 24, 2026 at 05:42:25PM +0300, Jarkko Sakkinen wrote:
> > invalidate_keyring_keys() does not hold keyring->sem while calling
> > keyring_read(), which is contrary to what keyring assumes from its callers,
> > and can lead to reoccuring bugs.
> > 
> > KEY_FLAG_KEEP alone does not e.g.,  protect from  the following call path:
> > 
> > 1. keyctl_keyring_move()
> > 2. key_move()
> > 3. __key_unlink()
> > 
> > Address the issue by guarding the critical section.
> > 
> > Fixes: 8cf57d7217c3 ("s390: add support for user-defined certificates")
> > Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
> > ---
> > This came up as a side product while working on assoc_array to
> > rhashtable migration and going through various callers of the keyring.
> > It's made by me but please keep in mind that I don't even have a
> > toolchain for s390 setup so it is based only on reading code and I have
> > not even compiled this.
> > 
> > Just wanted to clarify the background for this fix as I'm not a regular
> > contributor over here. If for any reason it turned out to be false
> > positive, I'm fine with that too.
> 
> It is not a false positive. There seem to be more bugs in the code.
> I'll take your patch and create a series with other fixes.

OK, great :-)

> 
> Thanks a lot!

You're welcome!

Br, Jarkko