[linux-yocto] [PATCH] serial: 8250: Fix serial8250 initialization crash

[Bruce Ashfield]

On 2019-01-23 8:43 p.m., He Zhe wrote:
> 
> 
> On 1/24/19 1:13 AM, Bruce Ashfield wrote:
>> On 1/23/19 2:45 AM, zhe.he at windriver.com wrote:
>>> From: He Zhe <zhe.he at windriver.com>
>>>
>>> https://lore.kernel.org/lkml/41c574bfdce7490597079dae8f328661@svr-chch-ex1.atlnz.lc/
>>>
>>> The initialization code of interrupt backoff work might reference NULL
>>> pointer and cause the following crash, if no port was found.
>>>
>>> [   10.017727] CPU 0 Unable to handle kernel paging request at virtual address 000001b0, epc == 807088e0, ra == 8070863c
>>> ---- snip ----
>>> [   11.704470] [<807088e0>] serial8250_register_8250_port+0x318/0x4ac
>>> [   11.747251] [<80708d74>] serial8250_probe+0x148/0x1c0
>>> [   11.789301] [<80728450>] platform_drv_probe+0x40/0x94
>>> [   11.830515] [<807264f8>] really_probe+0xf8/0x318
>>> [   11.870876] [<80726b7c>] __driver_attach+0x110/0x12c
>>> [   11.910960] [<80724374>] bus_for_each_dev+0x78/0xcc
>>> [   11.951134] [<80725958>] bus_add_driver+0x200/0x234
>>> [   11.989756] [<807273d8>] driver_register+0x84/0x148
>>> [   12.029832] [<80d72f84>] serial8250_init+0x138/0x198
>>> [   12.070447] [<80100e6c>] do_one_initcall+0x5c/0x2a0
>>> [   12.110104] [<80d3a208>] kernel_init_freeable+0x370/0x484
>>> [   12.150722] [<80a49420>] kernel_init+0x10/0xf8
>>> [   12.191517] [<8010756c>] ret_from_kernel_thread+0x14/0x1c
>>>
>>> This patch makes sure the initialization code can be reached only if a port
>>> is found.
>>>
>>> Fixes: 6d7f677a2afa ("serial: 8250: Rate limit serial port rx interrupts during input overruns")
>>> Signed-off-by: He Zhe <zhe.he at windriver.com>
>>> ---
>>> This is for standard/base. It has not been merged in mainline, but it's worth
>>> merging to linux-yocto first.
>>>
>>
>> Is this for 4.19 or linux-yocto-dev ?
> 
> linux-yocto-dev

ok. This is now merged.

Bruce

> 
> Zhe
> 
>>
>> Bruce
>>
>>>    drivers/tty/serial/8250/8250_core.c | 17 +++++++++--------
>>>    1 file changed, 9 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
>>> index 189ab12..e441221 100644
>>> --- a/drivers/tty/serial/8250/8250_core.c
>>> +++ b/drivers/tty/serial/8250/8250_core.c
>>> @@ -1070,15 +1070,16 @@ int serial8250_register_8250_port(struct uart_8250_port *up)
>>>                  ret = 0;
>>>            }
>>> -    }
>>>    -    /* Initialise interrupt backoff work if required */
>>> -    if (up->overrun_backoff_time_ms > 0) {
>>> -        uart->overrun_backoff_time_ms = up->overrun_backoff_time_ms;
>>> -        INIT_DELAYED_WORK(&uart->overrun_backoff,
>>> -                  serial_8250_overrun_backoff_work);
>>> -    } else {
>>> -        uart->overrun_backoff_time_ms = 0;
>>> +        /* Initialise interrupt backoff work if required */
>>> +        if (up->overrun_backoff_time_ms > 0) {
>>> +            uart->overrun_backoff_time_ms =
>>> +                up->overrun_backoff_time_ms;
>>> +            INIT_DELAYED_WORK(&uart->overrun_backoff,
>>> +                    serial_8250_overrun_backoff_work);
>>> +        } else {
>>> +            uart->overrun_backoff_time_ms = 0;
>>> +        }
>>>        }
>>>          mutex_unlock(&serial_mutex);
>>>
>>
>>
>