Re: [PATCH RESEND] scsi: megaraid_sas: fix panic on loading firmware crashdump

[Sumit Saxena]

On Mon, Jul 22, 2019 at 9:45 PM Junxiao Bi <junxiao.bi@xxxxxxxxxx> wrote:
>
> While loading fw crashdump in function fw_crash_buffer_show(),
> left bytes in one dma chunk was not checked, if copying size
> over it, overflow access will cause kernel panic.
>
> Signed-off-by: Junxiao Bi <junxiao.bi@xxxxxxxxxx>
Acked-by: Sumit Saxena <sumit.saxena@xxxxxxxxxxxx>
> ---
>  drivers/scsi/megaraid/megaraid_sas_base.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/scsi/megaraid/megaraid_sas_base.c b/drivers/scsi/megaraid/megaraid_sas_base.c
> index 80ab9700f1de..3eef0858fa8e 100644
> --- a/drivers/scsi/megaraid/megaraid_sas_base.c
> +++ b/drivers/scsi/megaraid/megaraid_sas_base.c
> @@ -3153,6 +3153,7 @@ fw_crash_buffer_show(struct device *cdev,
>                 (struct megasas_instance *) shost->hostdata;
>         u32 size;
>         unsigned long dmachunk = CRASH_DMA_BUF_SIZE;
> +       unsigned long chunk_left_bytes;
>         unsigned long src_addr;
>         unsigned long flags;
>         u32 buff_offset;
> @@ -3176,6 +3177,8 @@ fw_crash_buffer_show(struct device *cdev,
>         }
>
>         size = (instance->fw_crash_buffer_size * dmachunk) - buff_offset;
> +       chunk_left_bytes = dmachunk - (buff_offset % dmachunk);
> +       size = (size > chunk_left_bytes) ? chunk_left_bytes : size;
>         size = (size >= PAGE_SIZE) ? (PAGE_SIZE - 1) : size;
>
>         src_addr = (unsigned long)instance->crash_buf[buff_offset / dmachunk] +
> --
> 2.17.1
>