Re: [PATCH] HID: intel-ish-hid: ipc: Fix potential use-after-free in work function

[srinivas pandruvada <srinivas.pandruvada@linux.intel.com>]

On Mon, 2023-02-27 at 13:49 +1100, Reka Norman wrote:
> When a reset notify IPC message is received, the ISR schedules a work
> function and passes the ISHTP device to it via a global pointer
> ishtp_dev. If ish_probe() fails, the devm-managed device resources
> including ishtp_dev are freed, but the work is not cancelled, causing
> a
> use-after-free when the work function tries to access ishtp_dev. Use
> devm_work_autocancel() instead, so that the work is automatically
> cancelled if probe fails.
> 
> Signed-off-by: Reka Norman <rekanorman@chromium.org>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>

> ---
> 
>  drivers/hid/intel-ish-hid/ipc/ipc.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/hid/intel-ish-hid/ipc/ipc.c b/drivers/hid/intel-
> ish-hid/ipc/ipc.c
> index 15e14239af829..a49c6affd7c4c 100644
> --- a/drivers/hid/intel-ish-hid/ipc/ipc.c
> +++ b/drivers/hid/intel-ish-hid/ipc/ipc.c
> @@ -5,6 +5,7 @@
>   * Copyright (c) 2014-2016, Intel Corporation.
>   */
>  
> +#include <linux/devm-helpers.h>
>  #include <linux/sched.h>
>  #include <linux/spinlock.h>
>  #include <linux/delay.h>
> @@ -621,7 +622,6 @@ static void recv_ipc(struct ishtp_device *dev,
> uint32_t doorbell_val)
>         case MNG_RESET_NOTIFY:
>                 if (!ishtp_dev) {
>                         ishtp_dev = dev;
> -                       INIT_WORK(&fw_reset_work, fw_reset_work_fn);
>                 }
>                 schedule_work(&fw_reset_work);
>                 break;
> @@ -940,6 +940,7 @@ struct ishtp_device *ish_dev_init(struct pci_dev
> *pdev)
>  {
>         struct ishtp_device *dev;
>         int     i;
> +       int     ret;
>  
>         dev = devm_kzalloc(&pdev->dev,
>                            sizeof(struct ishtp_device) +
> sizeof(struct ish_hw),
> @@ -975,6 +976,12 @@ struct ishtp_device *ish_dev_init(struct pci_dev
> *pdev)
>                 list_add_tail(&tx_buf->link, &dev->wr_free_list);
>         }
>  
> +       ret = devm_work_autocancel(&pdev->dev, &fw_reset_work,
> fw_reset_work_fn);
> +       if (ret) {
> +               dev_err(dev->devc, "Failed to initialise FW reset
> work\n");
> +               return NULL;
> +       }
> +
>         dev->ops = &ish_hw_ops;
>         dev->devc = &pdev->dev;
>         dev->mtu = IPC_PAYLOAD_SIZE - sizeof(struct ishtp_msg_hdr);