Re: [PATCH] iio: adc: ltc2496: Fix possible null-ptr-deref in ltc2496_probe()

[Wei Yongjun <weiyongjun1@huawei.com>]

Hi Jonathan,

On 2022/10/2 21:27, Jonathan Cameron wrote:
> On Wed, 28 Sep 2022 04:09:48 +0000
> Wei Yongjun <weiyongjun@huaweicloud.com> wrote:
> 
>> From: Wei Yongjun <weiyongjun1@huawei.com>
>>
>> KASAN report null-ptr-deref as follows:
>>
>> KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
>> CPU: 0 PID: 282 Comm: python3 Tainted: G N 6.0.0-rc7-next-20220927+ #153
>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
>> RIP: 0010:ltc2497core_probe+0x77/0x440 [ltc2497_core]
>> Call Trace:
>>  <TASK>
>>  ltc2496_probe+0xf4/0x150
>>  spi_probe+0x158/0x1f0 drivers/spi/spi.c:421
>>  call_driver_probe drivers/base/dd.c:560 [inline]
>>  really_probe+0x207/0x750 drivers/base/dd.c:639
>>  __driver_probe_device+0x229/0x2a0 drivers/base/dd.c:778
>>  device_driver_attach+0xb8/0x1e0 drivers/base/dd.c:1105
>>
>> This happend when probe ltc2496 device with spi device id but without
>> dts, device_get_match_data() return null chip_info. Fix it by adding
>> null check for chip_info in ltc2496_probe().
> 
> What tree are you based on?  When I look at this file I'm not seeing a
> spi_device_id table so how is it matching?
> 

When no spi_device_id tables exists, the driver name in ltc2496_driver
can be used as the spi_device_id for matching.


> Also I'd prefer a more comprehensive fix that ensured the same data is
> available via the spi_device_id table and uses that if
> device_get_match_data() == NULL.
> 

Got it, will fix in next version.


Regards,
Wei Yongjun