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

[Jarkko Sakkinen <jarkko@kernel.org>]

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>

Thanks.

Br, Jarkko