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From: Guo Zhi <qtxuning1999@sjtu.edu.cn>
To: Greg KH <gregkh@linuxfoundation.org>,
	nsaenz@kernel.org, peterz@infradead.org, maz@kernel.org,
	bsegall@google.com, rdunlap@infradead.org, airlied@redhat.com,
	kan.liang@linux.intel.com, odin@uged.al, phil@raspberrypi.com
Cc: bcm-kernel-feedback-list@broadcom.com,
	linux-rpi-kernel@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] staging: vchip_arm: Fix misuse of %x
Date: Fri, 24 Sep 2021 10:57:18 +0800	[thread overview]
Message-ID: <3159c45c-b417-c157-e108-c0e12af2e122@sjtu.edu.cn> (raw)
In-Reply-To: <YUwOZjr06RV2BUi6@kroah.com>

On 2021/9/23 13:19, Greg KH wrote:
> On Thu, Sep 23, 2021 at 11:55:54AM +0800, Guo Zhi wrote:
>> Pointers should be printed with %p or %px rather than
>> cast to (unsigned long) and printed with %lx.
>> Change %lx to %pK to print the pointers.
>>
>> Signed-off-by: Guo Zhi <qtxuning1999@sjtu.edu.cn>
>> ---
>>   .../staging/vc04_services/interface/vchiq_arm/vchiq_arm.c | 8 ++++----
>>   1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
>> index b5aac862a29..408e5fe710b 100644
>> --- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
>> +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
>> @@ -591,11 +591,11 @@ service_callback(enum vchiq_reason reason, struct vchiq_header *header,
>>   		return VCHIQ_SUCCESS;
>>   
>>   	vchiq_log_trace(vchiq_arm_log_level,
>> -		"%s - service %lx(%d,%p), reason %d, header %lx, instance %lx, bulk_userdata %lx",
>> -		__func__, (unsigned long)user_service,
>> +		"%s - service %pK(%d,%p), reason %d, header %pK, instance %pK, bulk_userdata %pK",
>> +		__func__, user_service,
>>   		service->localport, user_service->userdata,
>> -		reason, (unsigned long)header,
>> -		(unsigned long)instance, (unsigned long)bulk_userdata);
>> +		reason, header,
>> +		instance, bulk_userdata);
> Why print this out at all?  What uses this?  Can it just be deleted?
>
> thanks,
>
> greg k-h

This information is printed for debugging usage.

But malicious user process can also print it through debugfs at 
/sys/kernel/debug.

As it can be used for debugging, it's a little radical to just delete.

Therefore, I suggest replacing %lx with %pK to avoid kernel address leakage.

thanks,

Guo



WARNING: multiple messages have this Message-ID (diff)
From: Guo Zhi <qtxuning1999@sjtu.edu.cn>
To: Greg KH <gregkh@linuxfoundation.org>,
	nsaenz@kernel.org, peterz@infradead.org, maz@kernel.org,
	bsegall@google.com, rdunlap@infradead.org, airlied@redhat.com,
	kan.liang@linux.intel.com, odin@uged.al, phil@raspberrypi.com
Cc: bcm-kernel-feedback-list@broadcom.com,
	linux-rpi-kernel@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] staging: vchip_arm: Fix misuse of %x
Date: Fri, 24 Sep 2021 10:57:18 +0800	[thread overview]
Message-ID: <3159c45c-b417-c157-e108-c0e12af2e122@sjtu.edu.cn> (raw)
In-Reply-To: <YUwOZjr06RV2BUi6@kroah.com>

On 2021/9/23 13:19, Greg KH wrote:
> On Thu, Sep 23, 2021 at 11:55:54AM +0800, Guo Zhi wrote:
>> Pointers should be printed with %p or %px rather than
>> cast to (unsigned long) and printed with %lx.
>> Change %lx to %pK to print the pointers.
>>
>> Signed-off-by: Guo Zhi <qtxuning1999@sjtu.edu.cn>
>> ---
>>   .../staging/vc04_services/interface/vchiq_arm/vchiq_arm.c | 8 ++++----
>>   1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
>> index b5aac862a29..408e5fe710b 100644
>> --- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
>> +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
>> @@ -591,11 +591,11 @@ service_callback(enum vchiq_reason reason, struct vchiq_header *header,
>>   		return VCHIQ_SUCCESS;
>>   
>>   	vchiq_log_trace(vchiq_arm_log_level,
>> -		"%s - service %lx(%d,%p), reason %d, header %lx, instance %lx, bulk_userdata %lx",
>> -		__func__, (unsigned long)user_service,
>> +		"%s - service %pK(%d,%p), reason %d, header %pK, instance %pK, bulk_userdata %pK",
>> +		__func__, user_service,
>>   		service->localport, user_service->userdata,
>> -		reason, (unsigned long)header,
>> -		(unsigned long)instance, (unsigned long)bulk_userdata);
>> +		reason, header,
>> +		instance, bulk_userdata);
> Why print this out at all?  What uses this?  Can it just be deleted?
>
> thanks,
>
> greg k-h

This information is printed for debugging usage.

But malicious user process can also print it through debugfs at 
/sys/kernel/debug.

As it can be used for debugging, it's a little radical to just delete.

Therefore, I suggest replacing %lx with %pK to avoid kernel address leakage.

thanks,

Guo



_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2021-09-24  2:57 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-23  3:55 [PATCH] staging: vchip_arm: Fix misuse of %x Guo Zhi
2021-09-23  3:55 ` Guo Zhi
2021-09-23  5:19 ` Greg KH
2021-09-23  5:19   ` Greg KH
2021-09-23 10:20   ` Stefan Wahren
2021-09-23 10:20     ` Stefan Wahren
2021-09-23 12:57   ` Guo Zhi
2021-09-23 12:57     ` Guo Zhi
2021-09-23 12:57     ` Guo Zhi
2021-09-23 13:13     ` Greg KH
2021-09-23 13:13       ` Greg KH
2021-09-24  2:57   ` Guo Zhi [this message]
2021-09-24  2:57     ` Guo Zhi
2021-09-27 15:35 ` Greg KH
2021-09-27 15:35   ` Greg KH

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