linux-kernel - Re: [PATCH v2] RDMA/rtrs: Fix double free in alloc

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Date:   Mon, 24 Jan 2022 22:55:00 +0100
From:   Jinpu Wang <jinpu.wang@...os.com>
To:     Miaoqian Lin <linmq006@...il.com>
Cc:     "Md. Haris Iqbal" <haris.iqbal@...os.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Danil Kipnis <danil.kipnis@...os.com>,
        linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] RDMA/rtrs: Fix double free in alloc_clt

On Mon, Jan 24, 2022 at 1:21 PM Miaoqian Lin <linmq006@...il.com> wrote:
>
> Callback function rtrs_clt_dev_release() in put_device()
> calls kfree(clt); to free memory. We shouldn't call kfree(clt) again.
>
> Fixes: 6a98d71daea1 ("RDMA/rtrs: client: main functionality")
> Signed-off-by: Miaoqian Lin <linmq006@...il.com>
Hi Miaoqian,
this is the complete fix.
https://lore.kernel.org/linux-rdma/Ye00cQ+VUkzh8JCH@unreal/T/#t

Thanks!
> ---
> Changes in v2:
> - call free_percpu() before put_device() to avoid UAF.
> ---
>  drivers/infiniband/ulp/rtrs/rtrs-clt.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/infiniband/ulp/rtrs/rtrs-clt.c b/drivers/infiniband/ulp/rtrs/rtrs-clt.c
> index 7c3f98e57889..aff04f566304 100644
> --- a/drivers/infiniband/ulp/rtrs/rtrs-clt.c
> +++ b/drivers/infiniband/ulp/rtrs/rtrs-clt.c
> @@ -2739,10 +2739,8 @@ static struct rtrs_clt_sess *alloc_clt(const char *sessname, size_t paths_num,
>          */
>         dev_set_uevent_suppress(&clt->dev, true);
>         err = device_register(&clt->dev);
> -       if (err) {
> -               put_device(&clt->dev);
> -               goto err;
> -       }
> +       if (err)
> +               goto err_register;
>
>         clt->kobj_paths = kobject_create_and_add("paths", &clt->dev.kobj);
>         if (!clt->kobj_paths) {
> @@ -2764,6 +2762,11 @@ static struct rtrs_clt_sess *alloc_clt(const char *sessname, size_t paths_num,
>  err:
>         free_percpu(clt->pcpu_path);
>         kfree(clt);
> +       goto ret;
> +err_register:
> +       free_percpu(clt->pcpu_path);
> +       put_device(&clt->dev);
> +ret:
>         return ERR_PTR(err);
>  }
>
> --
> 2.17.1
>