From: Kohei Enju <[email protected]>
Date: Mon, 2 Feb 2026 16:17:14 +0000
> When changing RX queue length via 'ethtool -G $DEV rx $NUM', a WARNING
> indicates the driver missed unregistering xdp_rxq_info [1], and then
> NULL pointer dereference panics the kernel. [2]
>
> The following sequence in ice_set_ringparam() triggers this bug.
> 1. Allocate new rx_rings
> 2. rx_rings[i] = *vsi->rx_rings[i];
> 3. ice_down() unregisters vsi->rx_rings[i]->xdp_rxq
> 4. ice_up() registers rx_ring[i]->xdp_rxq
> a. __xdp_rxq_info_reg() sees the copied state REG_STATE_REGISTERED
> and calls xdp_rxq_info_unreg() to fix it [1]
> b. xdp_unreg_mem_model() looks up the stale mem.id in rhashtable,
> which was already removed in step 3, causing NULL dereference [2]
>
> The root cause is that struct copying includes xdp_rxq_info which
> contains registration state that should not be duplicated.
>
> Fix by clearing xdp_rxq_info after copying the ring so it starts with
> REG_STATE_NEW instead of the stale REG_STATE_REGISTERED.
>
> [1]
> Missing unregister, handled but fix driver
> WARNING: net/core/xdp.c:182 at __xdp_rxq_info_reg+0x89/0x150, CPU#4:
> ethtool/1105
> [...]
> RIP: 0010:__xdp_rxq_info_reg+0x89/0x150
> [...]
> Call Trace:
> <TASK>
> ice_queue_mem_alloc+0x159/0x240
> ice_vsi_cfg_rxq+0xc3/0x160
> ice_vsi_cfg_rxqs+0x4f/0x70
> ice_up+0xd/0x20
> ice_set_ringparam+0x34f/0x4e0
>
> [2]
> BUG: kernel NULL pointer dereference, address: 0000000000000008
> [...]
> RIP: 0010:xdp_unreg_mem_model+0x113/0x340
> [...]
> Call Trace:
> <TASK>
> __xdp_rxq_info_reg+0xfd/0x150
> ice_queue_mem_alloc+0x159/0x240
> ice_vsi_cfg_rxq+0xc3/0x160
> ice_vsi_cfg_rxqs+0x4f/0x70
> ice_up+0xd/0x20
> ice_set_ringparam+0x34f/0x4e0
>
> Fixes: 111a8e2be488 ("ice: implement Rx queue management ops")
> Signed-off-by: Kohei Enju <[email protected]>
> ---
> I see the Fixes: commit exists in only tnguy/next-queue.git, so I'm
> sending this patch to iwl-next, not iwl-net.
>
> Also IIUC dev-queue in tnguy/next-queue.git is rebased continuously, so
> the commit hash will be stale soon, and I don't know how to handle this.
>
> I'd appreciate it if iwl-folks know the way to handle it. Thanks!
I either way need to respin the series once the window opens, I'll take
your fix into the series with the appropriate credits. Thanks!
Olek
