Re: [Intel-wired-lan] [PATCH net v2] ice: eswitch: fix use-after-free of metadata_dst in repr release

[Marcin Szycik <marcin.szycik@linux.intel.com>]

On 18/06/2026 16:50, Doruk Tan Ozturk wrote:
> ice_eswitch_release_repr() frees the port representor metadata_dst via
> metadata_dst_free(), which directly kfree()s the object and ignores the
> dst_entry refcount. The eswitch slow-path TX routine
> ice_eswitch_port_start_xmit() takes a reference on this dst with
> dst_hold() and attaches it to the skb via skb_dst_set(). If such an skb
> is still in flight (e.g. queued in a qdisc) when the representor is torn
> down, the metadata_dst is freed while the skb still points at it. When
> the skb is later freed, dst_release() operates on already-freed memory.
> 
> Replace metadata_dst_free() with dst_release() so the metadata_dst is
> freed only after the last reference is dropped. The dst subsystem frees
> metadata_dst objects from dst_destroy() once the refcount reaches zero
> (DST_METADATA is set by metadata_dst_alloc()).
> 
> Same class of bug and fix as commit c32b26aaa2f9 ("netfilter:
> nft_tunnel: fix use-after-free on object destroy").
> 
> Fixes: 1a1c40df2e80 ("ice: set and release switchdev environment")
> Cc: stable@vger.kernel.org
> Signed-off-by: Doruk Tan Ozturk <doruk@0sec.ai>
> Reviewed-by: Simon Horman <horms@kernel.org>

Reviewed-by: Marcin Szycik <marcin.szycik@linux.intel.com>

> ---
> v2:
>  - Correct the Fixes: tag to 1a1c40df2e80 ("ice: set and release
>    switchdev environment"); the previously cited fff292b47ac1 only moved
>    the affected code rather than introducing the unbalanced free, and the
>    bug dates back to when switchdev support was added (Simon Horman).
>  - Add Simon Horman's Reviewed-by. No functional change.
> 
>  drivers/net/ethernet/intel/ice/ice_eswitch.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/intel/ice/ice_eswitch.c b/drivers/net/ethernet/intel/ice/ice_eswitch.c
> index 2e4f0969035f..41b30a7ca4a9 100644
> --- a/drivers/net/ethernet/intel/ice/ice_eswitch.c
> +++ b/drivers/net/ethernet/intel/ice/ice_eswitch.c
> @@ -95,7 +95,7 @@ ice_eswitch_release_repr(struct ice_pf *pf, struct ice_repr *repr)
>  		return;
> 
>  	ice_vsi_update_security(vsi, ice_vsi_ctx_set_antispoof);
> -	metadata_dst_free(repr->dst);
> +	dst_release(&repr->dst->dst);
>  	repr->dst = NULL;
>  	ice_fltr_add_mac_and_broadcast(vsi, repr->parent_mac,
>  				       ICE_FWD_TO_VSI);
> --
> 2.43.0