linux-kernel - Re: [PATCH] serial: core: check if uart_get

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Date:   Tue, 7 Jun 2022 12:15:08 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Tom Rix <trix@...hat.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Peter Hurley <peter@...leysoftware.com>,
        "open list:SERIAL DRIVERS" <linux-serial@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        llvm@...ts.linux.dev
Subject: Re: [PATCH] serial: core: check if uart_get_info succeeds before using

On Sun, May 29, 2022 at 4:09 PM Tom Rix <trix@...hat.com> wrote:
>
> clang static analysis reports this representative issue
> drivers/tty/serial/serial_core.c:2818:9: warning: 3rd function call argument is an uninitialized value [core.CallAndMessage]
>         return sprintf(buf, "%d\n", tmp.iomem_reg_shift);
>                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> uart_get_info() is used the *show() functions.  When uart_get_info() fails, what is reported

in the ?

> is garbage.  So check if uart_get_info() succeeded.

...

> -       uart_get_info(port, &tmp);
> +       if (uart_get_info(port, &tmp))
> +               return 0;

I don't think this is correct. If something fails we need to inform the caller.

I think more about

int ret;

ret = uart_get_info(...);
if (ret)
  return ret;

But I haven't looked at the uart_get_info() implementation, so the
above might be wrong.

>         return sprintf(buf, "%d\n", tmp.baud_base * 16);

Ditto for the rest.

-- 
With Best Regards,
Andy Shevchenko