Re: [PATCH] KEYS: Fix signature input size for KEYCTL_PKEY_VERIFY

[Jarkko Sakkinen <jarkko@kernel.org>]

On Fri, Nov 13, 2026 at 09:45:05AM -0500, Stefan Berger wrote:
> 
> 
> On 11/13/26 9:11 AM, Jarkko Sakkinen wrote:
> > On Fri, Nov 13, 2026 at 04:10:12PM +0200, Jarkko Sakkinen wrote:
> > > On Fri, Nov 13, 2026 at 09:03:11AM -0500, Stefan Berger wrote:
> > > > Revert the changes made for signature verification in cb481e59ea6c back
> > > > to the old behavior where effectively the params->in2_len was set to the
> > > > length of the user provided buffer uparams.in2_len (out_len is an alias
> > > > for in2_len due to the union). We cannot use the max_sig_size in the
> > > > case of signature verification since this is neither the true size of the
> > > > input buffer nor would it pass tests of size indicators found in the ASN.1
> > > > in the buffer comparing against the input buffer size.
> > > > 
> > > > Fixes: cb481e59ea6c ("KEYS: fix overflow in keyctl_pkey_params_get_2()")
> > > > Cc: Jarkko Sakkinen <jarkko@kernel.org>
> > > > Cc: Florian Bauckholt <florian.bauckholt@cispa.de>
> > > > Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
> > > > ---
> > > >   security/keys/keyctl_pkey.c | 2 +-
> > > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > > > 
> > > > diff --git a/security/keys/keyctl_pkey.c b/security/keys/keyctl_pkey.c
> > > > index 15b6bf6399b5..794fa3d01911 100644
> > > > --- a/security/keys/keyctl_pkey.c
> > > > +++ b/security/keys/keyctl_pkey.c
> > > > @@ -160,7 +160,7 @@ static int keyctl_pkey_params_get_2(const struct keyctl_pkey_params __user *_par
> > > >   		    uparams.in2_len > info.max_sig_size)
> > > >   			return -EINVAL;
> > > > -		params->out_len = info.max_sig_size;
> > > > +		params->in2_len = uparams.in2_len;
> > > >   		break;
> > > >   	default:
> > > >   		return -EOPNOTSUPP;
> > > > -- 
> > > > 2.56.0
> > > > 
> > > 
> > > 
> > > Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
> > 
> > Did we have reported-by and closes tags for this?
> 
> Let me add this here for v2:
> 
> Link: https://lore.kernel.org/linux-crypto/473700a3-f5d7-4a7a-b89a-12c51adcc3df@cispa.de/T/#t
> Reported-by: Sashiko <sashiko-bot@kernel.org>
> 
> Once Florian added his Tested-by: to v1 should I then add this?
> 
> Cc: stable@vger.kernel.org

Nah, I don't care about Sashiko tags, no need to add em.

Go ahead and add Florian's tested-by.

Br, Jarkko