Re: [PATCH v3] KEYS: Fix key_reject_and_link() race with keyring restriction

[Jarkko Sakkinen]

On Sat, Oct 10, 2026 at 10:36:27PM +0300, Jarkko Sakkinen wrote:
> On Thu, Oct 08, 2026 at 02:03:51PM -0700, adrimg3196@xxxxxxxxx wrote:
> > The restrict_link check in key_reject_and_link() is done before taking
> > the keyring semaphore, racing with a concurrent keyring_restrict()
> > that installs the restriction while holding the semaphore in write
> > mode.
> > 
> > Move the check to after __key_link_lock(), so it is done under the
> > semaphore, matching the pattern used in __key_create_or_update().
> > 
> > Fixes: 5ac7eace2d00 ("KEYS: Add a facility to restrict new links into
> > a keyring")
> > Reviewed-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
> > Signed-off-by: Adrian Martinez <adrimg3196@xxxxxxxxx>
> > ---
> > Changelog:
> >  v3: Add Fixes tag and Reviewed-by; resend with clean patch (v2 was corrupt).
> >  v2: Resend with full patch (v1 arrived without the diff).
> > 
> >  security/keys/key.c | 17 ++++++++++++++---
> >  1 file changed, 14 insertions(+), 3 deletions(-)
> > 
> > diff --git a/security/keys/key.c b/security/keys/key.c
> > index 1234567..abcdefg 100644
> > --- a/security/keys/key.c
> > +++ b/security/keys/key.c
> > @@ -590,10 +590,17 @@ int key_reject_and_link(struct key *key,
> >  	ret = -EBUSY;
> > 
> >  	if (keyring) {
> > -		if (keyring->restrict_link)
> > -			return -EPERM;
> > -
> >  		link_ret = __key_link_lock(keyring, &key->index_key);
> >  		if (link_ret == 0) {
> > +			/*
> > +			 * Check the restriction under the keyring semaphore.
> > +			 * keyring_restrict() installs it while holding the
> > +			 * semaphore, so testing it beforehand races with a
> > +			 * concurrent restriction install.
> > +			 */
> > +			if (keyring->restrict_link) {
> > +				__key_link_end(keyring, &key->index_key, edit);
> > +				return -EPERM;
> > +			}
> >  			link_ret = __key_link_begin(keyring, &key->index_key, &edit);
> >  			if (link_ret < 0)
> >  				__key_link_end(keyring, &key->index_key, edit);
> 
> Thank you!
> 
> I applied this.
> 
> 
> Reviewed-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx>

But scripts/checkpatch.pl complains:

-------------------------------------------------------------------------------------
Commit fd17650a59fc ("KEYS: Fix key_reject_and_link() race with keyring restriction")
-------------------------------------------------------------------------------------
WARNING: From:/Signed-off-by: email name mismatch: 'From: "adrimg3196@xxxxxxxxx" <adrimg3196@xxxxxxxxx>' != 'Signed-off-by: Adrian Martinez <adrimg3196@xxxxxxxxx>'

total: 0 errors, 1 warnings, 0 checks, 21 lines checked

I can fix this up, so no need for new version but it is good
to be aware of this if you plan to send anything in the future.

Br, Jarkko