Re: [PATCH] HID: intel_ish-hid: Add check for ishtp_dma_tx_map

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

On Tue, 2022-11-22 at 21:48 +0800, Jiasheng Jiang wrote:
> As the kcalloc may return NULL pointer,
> it should be better to check the ishtp_dma_tx_map
> before use in order to avoid NULL pointer dereference.
> 
> Fixes: 3703f53b99e4 ("HID: intel_ish-hid: ISH Transport layer")
> Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
> ---
+Even Xu, We should do during alloc. Please try to submit a change for
that for later kernel rev as it will require error processing during
hbm dispatch.

>  drivers/hid/intel-ish-hid/ishtp/dma-if.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/hid/intel-ish-hid/ishtp/dma-if.c
> b/drivers/hid/intel-ish-hid/ishtp/dma-if.c
> index 40554c8daca0..00046cbfd4ed 100644
> --- a/drivers/hid/intel-ish-hid/ishtp/dma-if.c
> +++ b/drivers/hid/intel-ish-hid/ishtp/dma-if.c
> @@ -104,6 +104,11 @@ void *ishtp_cl_get_dma_send_buf(struct
> ishtp_device *dev,
>         int required_slots = (size / DMA_SLOT_SIZE)
>                 + 1 * (size % DMA_SLOT_SIZE != 0);
>  
> +       if (!dev->ishtp_dma_tx_map) {
> +               dev_err(dev->devc, "Fail to allocate Tx map\n");
> +               return NULL;
> +       }
> +
>         spin_lock_irqsave(&dev->ishtp_dma_tx_lock, flags);
>         for (i = 0; i <= (dev->ishtp_dma_num_slots - required_slots);
> i++) {
>                 free = 1;
> @@ -150,6 +155,11 @@ void ishtp_cl_release_dma_acked_mem(struct
> ishtp_device *dev,
>                 return;
>         }
>  
> +       if (!dev->ishtp_dma_tx_map) {
> +               dev_err(dev->devc, "Fail to allocate Tx map\n");
> +               return;
> +       }
> +
>         i = (msg_addr - dev->ishtp_host_dma_tx_buf) / DMA_SLOT_SIZE;
>         spin_lock_irqsave(&dev->ishtp_dma_tx_lock, flags);
>         for (j = 0; j < acked_slots; j++) {