RE: [Intel-wired-lan] [PATCH] idpf: fix UAF and double free in idpf_plug_core_aux_dev() error path

[Loktionov, Aleksandr]

> -----Original Message-----
> From: Intel-wired-lan <intel-wired-lan-bounces@xxxxxxxxxx> On Behalf
> Of Guangshuo Li
> Sent: Wednesday, March 18, 2026 4:52 PM
> To: Nguyen, Anthony L <anthony.l.nguyen@xxxxxxxxx>; Kitszel,
> Przemyslaw <przemyslaw.kitszel@xxxxxxxxx>; Andrew Lunn
> <andrew+netdev@xxxxxxx>; David S. Miller <davem@xxxxxxxxxxxxx>; Eric
> Dumazet <edumazet@xxxxxxxxxx>; Jakub Kicinski <kuba@xxxxxxxxxx>; Paolo
> Abeni <pabeni@xxxxxxxxxx>; Hay, Joshua A <joshua.a.hay@xxxxxxxxx>;
> Nikolova, Tatyana E <tatyana.e.nikolova@xxxxxxxxx>; Chittim, Madhu
> <madhu.chittim@xxxxxxxxx>; intel-wired-lan@xxxxxxxxxxxxxxxx;
> netdev@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Cc: Guangshuo Li <lgs201920130244@xxxxxxxxx>; stable@xxxxxxxxxxxxxxx
> Subject: [Intel-wired-lan] [PATCH] idpf: fix UAF and double free in
> idpf_plug_core_aux_dev() error path
> 
> If auxiliary_device_add() fails, idpf_plug_core_aux_dev() calls
> auxiliary_device_uninit(adev), whose release callback
> idpf_core_adev_release() frees the containing struct
> iidc_rdma_core_auxiliary_dev.
> 
> The current error path then accesses adev->id and later frees iadev
> again, which may lead to a use-after-free and double free.
> 
> Fix it by storing the allocated auxiliary device id in a local
> variable and avoiding direct freeing of iadev after
> auxiliary_device_uninit().
> 
> Fixes: f4312e6bfa2a ("idpf: implement core RDMA auxiliary dev create,
> init, and destroy")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Guangshuo Li <lgs201920130244@xxxxxxxxx>
> ---
>  drivers/net/ethernet/intel/idpf/idpf_idc.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/idpf/idpf_idc.c
> b/drivers/net/ethernet/intel/idpf/idpf_idc.c
> index 6dad0593f7f2..0fcbf9f1ddbb 100644
> --- a/drivers/net/ethernet/intel/idpf/idpf_idc.c
> +++ b/drivers/net/ethernet/intel/idpf/idpf_idc.c
> @@ -197,6 +197,7 @@ static int idpf_plug_core_aux_dev(struct
> iidc_rdma_core_dev_info *cdev_info)
>  	char name[IDPF_IDC_MAX_ADEV_NAME_LEN];
>  	struct auxiliary_device *adev;
>  	int ret;
> +	int id;
> 
>  	iadev = kzalloc(sizeof(*iadev), GFP_KERNEL);
>  	if (!iadev)
> @@ -211,12 +212,16 @@ static int idpf_plug_core_aux_dev(struct
> iidc_rdma_core_dev_info *cdev_info)
>  		pr_err("failed to allocate unique device ID for
> Auxiliary driver\n");
>  		goto err_ida_alloc;
>  	}
> -	adev->id = ret;
> +	id = ret;
> +	adev->id = id;
>  	adev->dev.release = idpf_core_adev_release;
>  	adev->dev.parent = &cdev_info->pdev->dev;
>  	sprintf(name, "%04x.rdma.core", cdev_info->pdev->vendor);
>  	adev->name = name;
> 
> +	/* iadev is owned by the auxiliary device */
> +	iadev = NULL;
> +
>  	ret = auxiliary_device_init(adev);
>  	if (ret)
>  		goto err_aux_dev_init;
> @@ -230,7 +235,7 @@ static int idpf_plug_core_aux_dev(struct
> iidc_rdma_core_dev_info *cdev_info)
>  err_aux_dev_add:
>  	auxiliary_device_uninit(adev);
>  err_aux_dev_init:
> -	ida_free(&idpf_idc_ida, adev->id);
> +	ida_free(&idpf_idc_ida, id);
>  err_ida_alloc:
>  	cdev_info->adev = NULL;
>  	kfree(iadev);
> --
> 2.43.0

Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@xxxxxxxxx>