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

> -----Original Message-----
> From: Intel-wired-lan <[email protected]> On Behalf Of
> Marcin Szycik
> Sent: Wednesday, June 24, 2026 1:36 PM
> To: Doruk Tan Ozturk <[email protected]>; Nguyen, Anthony L
> <[email protected]>; Kitszel, Przemyslaw
> <[email protected]>; [email protected];
> [email protected]; [email protected]; [email protected];
> [email protected]
> Cc: [email protected]; Drewek, Wojciech
> <[email protected]>; [email protected];
> [email protected]; [email protected];
> [email protected]; [email protected]
> Subject: Re: [Intel-wired-lan] [PATCH net v2] ice: eswitch: fix use-after-free of
> metadata_dst in repr release
> Importance: High
> 
> 
> 
> 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: [email protected]
> > Signed-off-by: Doruk Tan Ozturk <[email protected]>
> > Reviewed-by: Simon Horman <[email protected]>
> 
> Reviewed-by: Marcin Szycik <[email protected]>
> 
> > ---
> > 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


Tested-by: Patryk Holda <[email protected]>