[PATCH 2/2] firmware: zynqmp: fix write to an uninitialised pointer in ipi_req()

[Adrian Fiergolski]

On 15.10.2021 16:57, Michal Simek wrote:
> When a caller is not interested in the returned message, the ret_payload
> pointer is set to NULL in the u-boot-sources. In this case, under EL3, the
> memory from address 0x0 would be overwritten by ipi_req() with the returned
> IPI message, damaging the original data under this address. The patch, in
> case ret_payload is NULL, assigns the pointer to the array holding the IPI
> message being sent.
>
> Signed-off-by: Adrian Fiergolski <adrian.fiergolski at fastree3d.com>
> Signed-off-by: Michal Simek <michal.simek at xilinx.com>
Reviewed-by: Adrian Fiergolski <Adrian.Fiergolski at fastree3d.com>

Thanks,

Adrian

> ---
>
> Based on origin series from Adrian. That's why also adding his SoB line.
> https://lore.kernel.org/r/20211014124349.1429696-1-adrian.fiergolski@fastree3d.com
>
> Adrian: The patch is just suggestion how we could avoid that NULL pointer
> writes but done in ipi_req()
>
> ---
>  drivers/firmware/firmware-zynqmp.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/firmware/firmware-zynqmp.c b/drivers/firmware/firmware-zynqmp.c
> index 1391aab0a160..7e498d8169e8 100644
> --- a/drivers/firmware/firmware-zynqmp.c
> +++ b/drivers/firmware/firmware-zynqmp.c
> @@ -30,6 +30,10 @@ static int ipi_req(const u32 *req, size_t req_len, u32 *res, size_t res_maxlen)
>  {
>  	struct zynqmp_ipi_msg msg;
>  	int ret;
> +	u32 buffer[PAYLOAD_ARG_CNT];
> +
> +	if (!res)
> +		res = buffer;
>  
>  	if (req_len > PMUFW_PAYLOAD_ARG_CNT ||
>  	    res_maxlen > PMUFW_PAYLOAD_ARG_CNT)