Messages in this thread | | | Date | Wed, 12 Jul 2023 09:39:13 +0800 | Subject | Re: [PATCH 1/2] serial: sprd: Assign sprd_port after initialized to avoid wrong access | From | Baolin Wang <> |
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On 7/11/2023 10:57 AM, Chunyan Zhang wrote: > On Mon, 10 Jul 2023 at 17:57, Baolin Wang <baolin.wang@linux.alibaba.com> wrote: >> >> >> >> 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? > > This patch just does like this indeed, in the label of 'clean_port'. > Adding a local variable instead of using global pointer (sprd_port[]) > to store the virtual address allocated for sprd_port can avoid > overmany goto labels. > >> >>> >>> 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. > > The same virtual address stored in sprd_port[1] was reallocated to > sprd_port[2] after the UART1 probe returned failure. >
After more thinking, I understood your case. :)
But I see a nit in this patch, you added a 'clean_port' label to clear the resource for the fail-probe-port instead of sprd_remove(), however sprd_remove() will call sprd_rx_free_buf() to free the DMA buffer originally. I know the 2nd patch will add it back, but patch 1 is not git-bisect safe, right?
So I think you should also add sprd_rx_free_buf() under the 'clean_port' label in patch 1, then patch 2 moves the sprd_rx_free_buf() to the correct place.
>> 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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