Verifying user mode addresses

NTDEV
1

Hi all
can someody tell me if there is a way in the kernel
to tell whether a particular memory address is a valid
address or not ie
1: u can read /write to it
2: u can free it
3: acessing it will not cause page fault or ke bugcheck

Also another question is what does the line “Break due to Page Fault”
in a soft ice window mean.

Thanks in advance for ur help
Mayank

2

MmProbeForRead
MmProbeForWrite

HTH,
Vijay
----- Original Message -----
From: “Mayank Kumar”
To: “Windows System Software Devs Interest List”
Sent: Monday, April 26, 2004 11:03 AM
Subject: [ntdev] Verifying user mode addresses

> Hi all
> can someody tell me if there is a way in the kernel
> to tell whether a particular memory address is a valid
> address or not ie
> 1: u can read /write to it
> 2: u can free it
> 3: acessing it will not cause page fault or ke bugcheck
>
> Also another question is what does the line “Break due to Page Fault”
> in a soft ice window mean.
>
> Thanks in advance for ur help
> Mayank
>
>
> —
> Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256
>
> You are currently subscribed to ntdev as: xxxxx@hotmail.com
> To unsubscribe send a blank email to xxxxx@lists.osr.com
>

3

> -----Original Message-----

From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Vijay Anand
Sent: Monday, April 26, 2004 5:38 AM
To: Windows System Software Devs Interest List
Subject: Re: [ntdev] Verifying user mode addresses

MmProbeForRead
MmProbeForWrite

Not sufficient. Especially for (3). Given that the OP did not state any
other constraints on his problem, I’d say he cannot reliably accomplish his
goals. Is he locking the UVA into an MDL? Can he guarantee process context?
In fact what exactly is he trying to do?

HTH,
Vijay
----- Original Message -----
From: “Mayank Kumar”
> To: “Windows System Software Devs Interest List”
> Sent: Monday, April 26, 2004 11:03 AM
> Subject: [ntdev] Verifying user mode addresses
>
>
> > Hi all
> > can someody tell me if there is a way in the kernel
> > to tell whether a particular memory address is a valid
> > address or not ie
> > 1: u can read /write to it
> > 2: u can free it
> > 3: acessing it will not cause page fault or ke bugcheck
> >
> > Also another question is what does the line “Break due to
> Page Fault”
> > in a soft ice window mean.
> >
> > Thanks in advance for ur help
> > Mayank
> >
> >
> > —
> > Questions? First check the Kernel Driver FAQ at
> http://www.osronline.com/article.cfm?id=256
> >
> > You are currently subscribed to ntdev as:
> xxxxx@hotmail.com
> > To unsubscribe send a blank email to xxxxx@lists.osr.com
> >
>
> —
> Questions? First check the Kernel Driver FAQ at
> http://www.osronline.com/article.cfm?id=256
>
> You are currently subscribed to ntdev as: xxxxx@hollistech.com
> To unsubscribe send a blank email to xxxxx@lists.osr.com
>

4

Hi Roddy, Vijay
firstly i could not find these two apis in windows 2003
ddk.
Secondly what i want to do is just verify an address which has been passed
to me
from the User Mode via an IOCTL in BUFFERED_IO mode , whether that buffer
is a valid memory address so that i can write to it and also the amount
of memory size it is poiting to.
Is this possible or not ??

regds
Mayank

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com]On Behalf Of Mark Roddy
Sent: Monday, April 26, 2004 4:01 PM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] Verifying user mode addresses

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Vijay Anand
Sent: Monday, April 26, 2004 5:38 AM
To: Windows System Software Devs Interest List
Subject: Re: [ntdev] Verifying user mode addresses

MmProbeForRead
MmProbeForWrite

Not sufficient. Especially for (3). Given that the OP did not state any
other constraints on his problem, I’d say he cannot reliably accomplish his
goals. Is he locking the UVA into an MDL? Can he guarantee process context?
In fact what exactly is he trying to do?

HTH,
Vijay
----- Original Message -----
From: “Mayank Kumar”
> To: “Windows System Software Devs Interest List”
> Sent: Monday, April 26, 2004 11:03 AM
> Subject: [ntdev] Verifying user mode addresses
>
>
> > Hi all
> > can someody tell me if there is a way in the kernel
> > to tell whether a particular memory address is a valid
> > address or not ie
> > 1: u can read /write to it
> > 2: u can free it
> > 3: acessing it will not cause page fault or ke bugcheck
> >
> > Also another question is what does the line “Break due to
> Page Fault”
> > in a soft ice window mean.
> >
> > Thanks in advance for ur help
> > Mayank
> >
> >
> > —
> > Questions? First check the Kernel Driver FAQ at
> http://www.osronline.com/article.cfm?id=256
> >
> > You are currently subscribed to ntdev as:
> xxxxx@hotmail.com
> > To unsubscribe send a blank email to xxxxx@lists.osr.com
> >
>
> —
> Questions? First check the Kernel Driver FAQ at
> http://www.osronline.com/article.cfm?id=256
>
> You are currently subscribed to ntdev as: xxxxx@hollistech.com
> To unsubscribe send a blank email to xxxxx@lists.osr.com
>

—
Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256

You are currently subscribed to ntdev as:
xxxxx@intersolutions.stpn.soft.net
To unsubscribe send a blank email to xxxxx@lists.osr.com

5

That is because they are respectively ‘ProbeForRead’ and ‘ProbeForWrite’.

I think you are saying that you are embedding a user mode pointer in an
IOCTL METHOD_BUFFERED buffer. At this point the chorus cuts in with:

CHORUS: Vijay, Don’t Do That! Bad Vijay! Bad!

Your approach might be typical in the Unix world, but it is considered
strictly Bad Form over here in our world.

Regardless, you cannot tell from a VA what the valid length of the VA is.

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Mayank Kumar
Sent: Tuesday, April 27, 2004 1:14 AM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] Verifying user mode addresses

Hi Roddy, Vijay
firstly i could not find these two apis in windows 2003 ddk.
Secondly what i want to do is just verify an address which
has been passed to me from the User Mode via an IOCTL in
BUFFERED_IO mode , whether that buffer is a valid memory
address so that i can write to it and also the amount of
memory size it is poiting to.
Is this possible or not ??

regds
Mayank

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com]On Behalf Of Mark Roddy
Sent: Monday, April 26, 2004 4:01 PM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] Verifying user mode addresses

> -----Original Message-----
> From: xxxxx@lists.osr.com
> [mailto:xxxxx@lists.osr.com] On Behalf Of Vijay Anand
> Sent: Monday, April 26, 2004 5:38 AM
> To: Windows System Software Devs Interest List
> Subject: Re: [ntdev] Verifying user mode addresses
>
> MmProbeForRead
> MmProbeForWrite

Not sufficient. Especially for (3). Given that the OP did not
state any other constraints on his problem, I’d say he cannot
reliably accomplish his goals. Is he locking the UVA into an
MDL? Can he guarantee process context?
In fact what exactly is he trying to do?

>
> HTH,
> Vijay
> ----- Original Message -----
> From: “Mayank Kumar”
> > To: “Windows System Software Devs Interest List”
>
> > Sent: Monday, April 26, 2004 11:03 AM
> > Subject: [ntdev] Verifying user mode addresses
> >
> >
> > > Hi all
> > > can someody tell me if there is a way in the kernel to
> tell whether
> > > a particular memory address is a valid address or not ie
> > > 1: u can read /write to it
> > > 2: u can free it
> > > 3: acessing it will not cause page fault or ke bugcheck
> > >
> > > Also another question is what does the line “Break due to
> > Page Fault”
> > > in a soft ice window mean.
> > >
> > > Thanks in advance for ur help
> > > Mayank
> > >
> > >
> > > —
> > > Questions? First check the Kernel Driver FAQ at
> > http://www.osronline.com/article.cfm?id=256
> > >
> > > You are currently subscribed to ntdev as:
> > xxxxx@hotmail.com
> > > To unsubscribe send a blank email to
> xxxxx@lists.osr.com
> > >
> >
> > —
> > Questions? First check the Kernel Driver FAQ at
> > http://www.osronline.com/article.cfm?id=256
> >
> > You are currently subscribed to ntdev as: xxxxx@hollistech.com To
> > unsubscribe send a blank email to xxxxx@lists.osr.com
> >
>
>
>
>
> —
> Questions? First check the Kernel Driver FAQ at
> http://www.osronline.com/article.cfm?id=256
>
> You are currently subscribed to ntdev as:
> xxxxx@intersolutions.stpn.soft.net
> To unsubscribe send a blank email to xxxxx@lists.osr.com
>
>
> —
> Questions? First check the Kernel Driver FAQ at
> http://www.osronline.com/article.cfm?id=256
>
> You are currently subscribed to ntdev as:
> xxxxx@hollistech.com To unsubscribe send a blank email to
> xxxxx@lists.osr.com
>