linux-kernel - Re: [PATCH 3/3] i2c: i801: avoid panic if ioreamp fails

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Message-ID: <164bb498-35dc-b226-4adb-3d743f4790a1@huawei.com>
Date:   Fri, 10 May 2019 17:35:46 +0800
From:   Kefeng Wang <wangkefeng.wang@...wei.com>
To:     Jean Delvare <jdelvare@...e.de>
CC:     <linux-kernel@...r.kernel.org>, Wolfram Sang <wsa@...-dreams.de>,
        <linux-i2c@...r.kernel.org>, Hulk Robot <hulkci@...wei.com>
Subject: Re: [PATCH 3/3] i2c: i801: avoid panic if ioreamp fails


On 2019/5/10 16:09, Jean Delvare wrote:
> Hi Kefeng,
>
> On Fri, 10 May 2019 11:03:20 +0800, Kefeng Wang wrote:
>> If ioremap fails, NULL pointer dereference will happen and
>> leading to a kernel panic when access the virtual address
>> in check_signature().
>>
>> Fix it by check the return value of ioremap.
>>
>> Cc: Jean Delvare <jdelvare@...e.com>
>> Cc: Wolfram Sang <wsa@...-dreams.de>
>> Cc: linux-i2c@...r.kernel.org
>> Reported-by: Hulk Robot <hulkci@...wei.com>
>> Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>
>> ---
>>  drivers/i2c/busses/i2c-i801.c | 5 ++++-
>>  1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
>> index 679c6c41f64b..fc6ccb8aba17 100644
>> --- a/drivers/i2c/busses/i2c-i801.c
>> +++ b/drivers/i2c/busses/i2c-i801.c
>> @@ -1068,7 +1068,10 @@ static void __init input_apanel_init(void)
>>  	void __iomem *bios;
>>  	const void __iomem *p;
>>  
>> -	bios = ioremap(0xF0000, 0x10000); /* Can't fail */
>> +	bios = ioremap(0xF0000, 0x10000);
>> +	if (!base)
> That would be "if (!bios)". Please don't send patches without at least
> test-building the result.
sorry,  copy error.

> We don't need this anyway. The comment says it can't fail, so why
> bother checking for a condition which will never happen?

The ioremap could fails due to no memory, our inner test robot(enable FAULT_INJECTION)

find this issue.


>
>> +		return -ENOMEM;
>> +
>>  	p = bios_signature(bios);
>>  	if (p) {
>>  		/* just use the first address */
>