Re: [iwl-net v2 5/5] ice: fix using untrusted value of pkt_len in ice_vc_fdir_parse_raw()

[Simon Horman <horms@kernel.org>]

On Tue, Feb 25, 2025 at 10:08:49AM +0100, Martyna Szapar-Mudlaw wrote:
> From: Mateusz Polchlopek <mateusz.polchlopek@intel.com>
> 
> Fix using the untrusted value of proto->raw.pkt_len in function
> ice_vc_fdir_parse_raw() by verifying if it does not exceed the
> VIRTCHNL_MAX_SIZE_RAW_PACKET value.
> 
> Fixes: 99f419df8a5c ("ice: enable FDIR filters from raw binary patterns for VFs")
> Signed-off-by: Mateusz Polchlopek <mateusz.polchlopek@intel.com>
> Signed-off-by: Martyna Szapar-Mudlaw <martyna.szapar-mudlaw@linux.intel.com>
> ---
>  .../ethernet/intel/ice/ice_virtchnl_fdir.c    | 25 +++++++++++++------
>  1 file changed, 17 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/ice/ice_virtchnl_fdir.c b/drivers/net/ethernet/intel/ice/ice_virtchnl_fdir.c
> index 14e3f0f89c78..6250629ee8f9 100644
> --- a/drivers/net/ethernet/intel/ice/ice_virtchnl_fdir.c
> +++ b/drivers/net/ethernet/intel/ice/ice_virtchnl_fdir.c
> @@ -835,18 +835,27 @@ ice_vc_fdir_parse_raw(struct ice_vf *vf,
>  	u8 *pkt_buf, *msk_buf __free(kfree);
>  	struct ice_parser_result rslt;
>  	struct ice_pf *pf = vf->pf;
> +	u16 pkt_len, udp_port = 0;
>  	struct ice_parser *psr;
>  	int status = -ENOMEM;
>  	struct ice_hw *hw;
> -	u16 udp_port = 0;
>  
> -	pkt_buf = kzalloc(proto->raw.pkt_len, GFP_KERNEL);
> -	msk_buf = kzalloc(proto->raw.pkt_len, GFP_KERNEL);
> +	if (!proto->raw.pkt_len)
> +		return -EINVAL;

Hi Martyna,

It seems to me that the use of __free() above will result in
kfree(msk_buf) being called here. But msk_buf is not initialised at this
point.

My suggest would be to drop the use of __free().
But if not, I think that in order to be safe it would be best to do this
(completely untested;

	u8 *pkt_buf, *msk_buf __free(kfree) = NULL;

...