On Fri, Sep 25, 2020 at 06:31:09PM +0900, Nobuhiro Iwamatsu wrote:
> From: Lukas Wunner <lukas@xxxxxxxxx>
>
> commit e0a851fe6b9b619527bd928aa93caaddd003f70c upstream.
>
> If the call to uart_add_one_port() in serial8250_register_8250_port()
> fails, a half-initialized entry in the serial_8250ports[] array is left
> behind.
>
> A subsequent reprobe of the same serial port causes that entry to be
> reused. Because uart->port.dev is set, uart_remove_one_port() is called
> for the half-initialized entry and bails out with an error message:
>
> bcm2835-aux-uart 3f215040.serial: Removing wrong port: (null) != (ptrval)
>
> The same happens on failure of mctrl_gpio_init() since commit
> 4a96895f74c9 ("tty/serial/8250: use mctrl_gpio helpers").
>
> Fix by zeroing the uart->port.dev pointer in the probe error path.
>
> The bug was introduced in v2.6.10 by historical commit befff6f5bf5f
> ("[SERIAL] Add new port registration/unregistration functions."):
> https://git.kernel.org/tglx/history/c/befff6f5bf5f
>
> The commit added an unconditional call to uart_remove_one_port() in
> serial8250_register_port(). In v3.7, commit 835d844d1a28 ("8250_pnp:
> do pnp probe before legacy probe") made that call conditional on
> uart->port.dev which allows me to fix the issue by zeroing that pointer
> in the error path. Thus, the present commit will fix the problem as far
> back as v3.7 whereas still older versions need to also cherry-pick
> 835d844d1a28.
>
> Fixes: 835d844d1a28 ("8250_pnp: do pnp probe before legacy probe")
> Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx # v2.6.10
> Cc: stable@xxxxxxxxxxxxxxx # v2.6.10: 835d844d1a28: 8250_pnp: do pnp probe before legacy
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> Link: https://lore.kernel.org/r/b4a072013ee1a1d13ee06b4325afb19bda57ca1b.1589285873.git.lukas@xxxxxxxxx
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> [iwamatsu: Backported to 4.14, 4.19: adjust context]
> Signed-off-by: Nobuhiro Iwamatsu (CIP) <nobuhiro1.iwamatsu@xxxxxxxxxxxxx>
Thanks, now queue dup.
greg k-h
