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SubjectRe: [PATCH 1/2] serial: sprd: Assign sprd_port after initialized to avoid wrong access
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On 7/10/2023 4:03 PM, Chunyan Zhang wrote:
> The global pointer 'sprd_port' maybe not zero when sprd_probe returns
> fail, that is a risk for sprd_port to be accessed afterward, and will
> lead unexpected errors.
>
> For example:
>
> There're two UART ports, UART1 is used for console and configured in kernel
> command line, i.e. "console=";
>
> The UART1 probe fail and the memory allocated to sprd_port[1] was released,
> but sprd_port[1] was not set to NULL;

IMO, we should just set sprd_port[1] to be NULL, which seems simpler?

>
> In UART2 probe, the same virtual address was allocated to sprd_port[2],
> and UART2 probe process finally will go into sprd_console_setup() to
> register UART1 as console since it is configured as preferred console
> (filled to console_cmdline[]), but the console parameters (sprd_port[1])
> actually belongs to UART2.

I'm confusing why the console parameters belongs to UART2? Since the
console_cmdline[] will specify the serial index, that belongs to UART1.
Please correct me if I miss something.

> So move the sprd_port[] assignment to where the port already initialized
> can avoid the above issue.
>
> Fixes: b7396a38fb28 ("tty/serial: Add Spreadtrum sc9836-uart driver support")
> Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
> ---
> drivers/tty/serial/sprd_serial.c | 24 ++++++++++++++++--------
> 1 file changed, 16 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/tty/serial/sprd_serial.c b/drivers/tty/serial/sprd_serial.c
> index b58f51296ace..942808517393 100644
> --- a/drivers/tty/serial/sprd_serial.c
> +++ b/drivers/tty/serial/sprd_serial.c
> @@ -1106,7 +1106,7 @@ static bool sprd_uart_is_console(struct uart_port *uport)
> static int sprd_clk_init(struct uart_port *uport)
> {
> struct clk *clk_uart, *clk_parent;
> - struct sprd_uart_port *u = sprd_port[uport->line];
> + struct sprd_uart_port *u = container_of(uport, struct sprd_uart_port, port);
>
> clk_uart = devm_clk_get(uport->dev, "uart");
> if (IS_ERR(clk_uart)) {
> @@ -1149,22 +1149,22 @@ static int sprd_probe(struct platform_device *pdev)
> {
> struct resource *res;
> struct uart_port *up;
> + struct sprd_uart_port *sport;
> int irq;
> int index;
> int ret;
>
> index = of_alias_get_id(pdev->dev.of_node, "serial");
> - if (index < 0 || index >= ARRAY_SIZE(sprd_port)) {
> + if (index < 0 || index >= UART_NR_MAX) {
> dev_err(&pdev->dev, "got a wrong serial alias id %d\n", index);
> return -EINVAL;
> }
>
> - sprd_port[index] = devm_kzalloc(&pdev->dev, sizeof(*sprd_port[index]),
> - GFP_KERNEL);
> - if (!sprd_port[index])
> + sport = devm_kzalloc(&pdev->dev, sizeof(*sport), GFP_KERNEL);
> + if (!sport)
> return -ENOMEM;
>
> - up = &sprd_port[index]->port;
> + up = &sport->port;
> up->dev = &pdev->dev;
> up->line = index;
> up->type = PORT_SPRD;
> @@ -1195,7 +1195,7 @@ static int sprd_probe(struct platform_device *pdev)
> * Allocate one dma buffer to prepare for receive transfer, in case
> * memory allocation failure at runtime.
> */
> - ret = sprd_rx_alloc_buf(sprd_port[index]);
> + ret = sprd_rx_alloc_buf(sport);
> if (ret)
> return ret;
>
> @@ -1208,12 +1208,20 @@ static int sprd_probe(struct platform_device *pdev)
> }
> sprd_ports_num++;
>
> + sprd_port[index] = sport;
> +
> ret = uart_add_one_port(&sprd_uart_driver, up);
> if (ret)
> - sprd_remove(pdev);
> + goto clean_port;
>
> platform_set_drvdata(pdev, up);
>
> + return 0;
> +
> +clean_port:
> + sprd_port[index] = NULL;
> + sprd_ports_num--;
> + uart_unregister_driver(&sprd_uart_driver);
> return ret;
> }
>

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