NACK: [F][PATCH 1/1] serial: imx: Introduce timeout when waiting on transmitter empty

[Massimiliano Pellizzer]

On Tue, 12 Nov 2024 at 23:21, Yuxuan Luo <yuxuan.luo at canonical.com> wrote:
>
> From: Esben Haabendal <esben at geanix.com>
>
> By waiting at most 1 second for USR2_TXDC to be set, we avoid a potential
> deadlock.
>
> In case of the timeout, there is not much we can do, so we simply ignore
> the transmitter state and optimistically try to continue.
>
> Signed-off-by: Esben Haabendal <esben at geanix.com>
> Acked-by: Marc Kleine-Budde <mkl at pengutronix.de>
> Link: https://lore.kernel.org/r/919647898c337a46604edcabaf13d42d80c0915d.1712837613.git.esben@geanix.com
> Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
> (backported from commit e533e4c62e9993e62e947ae9bbec34e4c7ae81c2)
> [yuxuan.luo: read_poll_timeout_atomic() function is not introduced until
> 57a29df34146 (“iopoll: Introduce read_poll_timeout_atomic macro”),
> however, readx_poll_timeout_atomic() can be used interchangeably.
> ]
> CVE-2024-40967
> Signed-off-by: Yuxuan Luo <yuxuan.luo at canonical.com>
> ---
>  drivers/tty/serial/imx.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
> index 80cb72350ceaa..990d58fdeec61 100644
> --- a/drivers/tty/serial/imx.c
> +++ b/drivers/tty/serial/imx.c
> @@ -30,6 +30,7 @@
>  #include <linux/of.h>
>  #include <linux/of_device.h>
>  #include <linux/io.h>
> +#include <linux/iopoll.h>
>  #include <linux/dma-mapping.h>
>
>  #include <asm/irq.h>
> @@ -1939,7 +1940,7 @@ imx_uart_console_write(struct console *co, const char *s, unsigned int count)
>  {
>         struct imx_port *sport = imx_uart_ports[co->index];
>         struct imx_port_ucrs old_ucr;
> -       unsigned int ucr1;
> +       unsigned int ucr1, usr2;
>         unsigned long flags = 0;
>         int locked = 1;
>
> @@ -1971,8 +1972,8 @@ imx_uart_console_write(struct console *co, const char *s, unsigned int count)
>          *      Finally, wait for transmitter to become empty
>          *      and restore UCR1/2/3
>          */
> -       while (!(imx_uart_readl(sport, USR2) & USR2_TXDC));
> -
> +       readx_poll_timeout_atomic(imx_uart_readl, usr2, usr2 & USR2_TXDC,
> +                                0, USEC_PER_SEC, false, sport, USR2);

The usage of readx_poll_timeout_atomic() introduces an error which
does not allow the kernel to compile:
error: macro "readx_poll_timeout_atomic" passed 8 arguments, but takes just 6
In order to trigger the compile-time error it is necessary to enable
CONFIG_SERIAL_IMX_CONSOLE.

>         imx_uart_ucrs_restore(sport, &old_ucr);
>
>         if (locked)
> --
> 2.43.0
>
>
> --
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The patch is missing the [SRU] tag in the subject.

-- 
Massimiliano Pellizzer