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

[Simon Horman <horms@kernel.org>]

On Mon, Jun 15, 2026 at 04:05:32PM +0200, 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").

I think that the commit cited above moves the code in question around
but did not introduce the call to dst_release. And I think that this
bug goes back to when switchdev support was added.

I would suggest:

Fixes: 1a1c40df2e80 ("ice: set and release switchdev environment")

> Cc: stable@vger.kernel.org
> Signed-off-by: Doruk Tan Ozturk <doruk@0sec.ai>

Otherwise, this looks good to me.

Reviewed-by: Simon Horman <horms@kernel.org>