RE: [PATCH] usb: cdnsp: Fix segmentation fault in cdns_lost_power function

From: Pawel Laszczak <pawell@cadence.com>
To: Peter Chen <peter.chen@kernel.org>
Cc: "a-govindraju@ti.com" <a-govindraju@ti.com>,
	"frank.li@nxp.com" <frank.li@nxp.com>,
	"rogerq@kernel.org" <rogerq@kernel.org>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"stable@vger.kernel.org" <stable@vger.kernel.org>
Subject: RE: [PATCH] usb: cdnsp: Fix segmentation fault in cdns_lost_power function
Date: Wed, 12 Jan 2022 13:13:10 +0000	[thread overview]
Message-ID: <BYAPR07MB5381D8455AF977200D503D15DD529@BYAPR07MB5381.namprd07.prod.outlook.com> (raw)
In-Reply-To: <20220112125615.GC3796@Peter>

>
>On 22-01-11 10:07:37, Pawel Laszczak wrote:
>> From: Pawel Laszczak <pawell@cadence.com>
>>
>> CDNSP driver read not initialized cdns->otg_v0_regs
>> which lead to segmentation fault. Patch fixes this issue.
>>
>> Fixes: 2cf2581cd229 ("usb: cdns3: add power lost support for system resume")
>> cc: <stable@vger.kernel.org>
>> Signed-off-by: Pawel Laszczak <pawell@cadence.com>
>> ---
>>  drivers/usb/cdns3/drd.c | 6 +++---
>>  1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/usb/cdns3/drd.c b/drivers/usb/cdns3/drd.c
>> index 55c73b1d8704..d00ff98dffab 100644
>> --- a/drivers/usb/cdns3/drd.c
>> +++ b/drivers/usb/cdns3/drd.c
>> @@ -483,11 +483,11 @@ int cdns_drd_exit(struct cdns *cdns)
>>  /* Indicate the cdns3 core was power lost before */
>>  bool cdns_power_is_lost(struct cdns *cdns)
>>  {
>> -	if (cdns->version == CDNS3_CONTROLLER_V1) {
>> -		if (!(readl(&cdns->otg_v1_regs->simulate) & BIT(0)))
>> +	if (cdns->version == CDNS3_CONTROLLER_V0) {
>> +		if (!(readl(&cdns->otg_v0_regs->simulate) & BIT(0)))
>>  			return true;
>>  	} else {
>> -		if (!(readl(&cdns->otg_v0_regs->simulate) & BIT(0)))
>> +		if (!(readl(&cdns->otg_v1_regs->simulate) & BIT(0)))
>>  			return true;
>>  	}
>>  	return false;
>> --
>
>Pawel, may this lead cdns driver segment fault?
>

Yes, we can observe such situation for CDNSP driver on simulation. 
As you know, it is a common code and driver support two version  of register map for DRD.

If cdns->version  == CDNSP_CONTROLLER_V2 (for CNDSP) the cdns->otg_v0_regs is NULL.
It will cause segmentation fault. 

I didn't analyze why this issue was not observed on my FPGA testing board.

Regards,

Pawel Laszczak  