HELP !! pb calling eVC++ DLL from VB.NET on compact framework

  • Thread starter Thread starter Rick
  • Start date Start date
R

Rick

hi all !

i need your HELP ! (it's long to explain but it's needed)

i have a big problem (for me) with my APP/DLL

i have made an Application with VB.NET for Compact framework that call an
DLL written in eVC++ 4.

the pb is i get a "First-chance exception ... Access violation" sometimes...

before my VB app are small (and i haven't the pb) but now is bigger (and i
have the pb all the time).

when i debug the DLL, at the exception if i continu, i often get a "stack
overflow"..

i have read many things on the net but i haven't found a solution for the
pb. it seem its a limit of 4k(or 64k) boundary page pb with the stack..
here the start of my DLL function :

char __declspec(dllexport) f_com_ReadAcq(char voie,double * pValeurs, int
*nbValeur)
{
UCHAR buffer[120000];
long sizeBuf=0;

ReceiveData_GetLast(&tdReceiveMemory, buffer,500, RECEIVE_DATA_ACQ, voie
,&sizeBuf);
...
...
}

in ReceiveData_GetLast i do some memcpy to "buffer" and it's these memcpy
that do exception...i have try to replace the memcpy by a soft loop then it
crash at same time..

the DLL function is called from many place on the vb.net app then in one
case (always the same) it work...

when it work, the &buffer = 0x2207F2CC
when it crash the &buffer = 0x22011f8c
when it crash the pointer to buffer = 0x22012000

i mean it's the 1FFF to 2000 boudary that cause crash...(4k page ??)

i mean i can use malloc to allocate my 120k buffer, but i'm afraid for the
rest of development...if i have only 116 bytes of local memory available
(0x22012000 - 0x22011f8c)...then this problem can appairs later in
development even if i make all array with malloc............

can it be VB.NET that fill the stack ?and how i can do to "free" some bytes
of the stack before calling DLL...?

thank a lot for all people that can help me....(i'm on this pb since 3 days
now and my app is not finished.....)

Eric BOUXIROT
(sorry for my bad english)

you can answer me at (e-mail address removed)
 
I don't think it's related to VB and pages. That seems to be a very common
bug in your native code called "buffer overflow".

Here's an example:

UCHAR buffer[10];
...
bufferr[100] = 0; // Oops.
memcpy (buffer, NULL, 100); // Oops and... oops.

Most likely memcpy() in ReceiveData_GetLast() copies more than 120000 bytes
for some reason or uses invalid pointer(s).
Add some verification code to ReceiveData_GetLast() to verify array
boundaries/pointers and pop up an assert in case of a problem.
That would help you figure out what's wrong. Also, it's a good idea to add
some check and return an error if data appears to be incorrect.

You should pass buffer size to ReceiveData_GetLast() so it won't copy too
much:

UCHAR buffer[120000];
...
long sizeBuf=sizeof(buffer);
...

In ReceiveData_GetLast():

size = ... ; // Where it's coming from? Can it be wrong?
source = ... ; // Where it's coming from? Can it be wrong?

ASSERT (buffer != NULL);
ASSERT (source != NULL);
ASSERT (sizeBuf > size);

// consider adding check and return an error instead of crashing…
….
memcpy (buffer, source, size);

Best regards,

Ilya

This posting is provided "AS IS" with no warranties, and confers no rights.

--------------------
Reply-To: "Rick" <[email protected]>
From: "Rick" <[email protected]>
Newsgroups: microsoft.public.windowsce.embedded.vc,microsoft.public.dotnet.framework.com
pactframework,microsoft.public.dotnet.languages.vb,microsoft.public.windowsc
e.embedded.vb
Followup-To: microsoft.public.windowsce.embedded.vc
Subject: HELP !! pb calling eVC++ DLL from VB.NET on compact framework
Date: Tue, 30 Nov 2004 11:18:06 +0100
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hi all !

i need your HELP ! (it's long to explain but it's needed)

i have a big problem (for me) with my APP/DLL

i have made an Application with VB.NET for Compact framework that call an
DLL written in eVC++ 4.

the pb is i get a "First-chance exception ... Access violation" sometimes...

before my VB app are small (and i haven't the pb) but now is bigger (and i
have the pb all the time).

when i debug the DLL, at the exception if i continu, i often get a "stack
overflow"..

i have read many things on the net but i haven't found a solution for the
pb. it seem its a limit of 4k(or 64k) boundary page pb with the stack..
here the start of my DLL function :

char __declspec(dllexport) f_com_ReadAcq(char voie,double * pValeurs, int
*nbValeur)
{
UCHAR buffer[120000];
long sizeBuf=0;

ReceiveData_GetLast(&tdReceiveMemory, buffer,500, RECEIVE_DATA_ACQ, voie
,&sizeBuf);
..
..
}

in ReceiveData_GetLast i do some memcpy to "buffer" and it's these memcpy
that do exception...i have try to replace the memcpy by a soft loop then it
crash at same time..

the DLL function is called from many place on the vb.net app then in one
case (always the same) it work...

when it work, the &buffer = 0x2207F2CC
when it crash the &buffer = 0x22011f8c
when it crash the pointer to buffer = 0x22012000

i mean it's the 1FFF to 2000 boudary that cause crash...(4k page ??)

i mean i can use malloc to allocate my 120k buffer, but i'm afraid for the
rest of development...if i have only 116 bytes of local memory available
(0x22012000 - 0x22011f8c)...then this problem can appairs later in
development even if i make all array with malloc............

can it be VB.NET that fill the stack ?and how i can do to "free" some bytes
of the stack before calling DLL...?

thank a lot for all people that can help me....(i'm on this pb since 3 days
now and my app is not finished.....)

Eric BOUXIROT
(sorry for my bad english)

you can answer me at (e-mail address removed)
Click to expand...
 
Ilya,

This thread is an orphan. The continuing thread is in the eVC newsgroup.
In fact, though, the allocation of the local, *not* its use, is responsible
for the exception. See my code to duplicate the problem in the other
newsgroup (same thread name).

Paul T.

"Ilya Tumanov [MS]" said:
I don't think it's related to VB and pages. That seems to be a very common
bug in your native code called "buffer overflow".

Here's an example:

UCHAR buffer[10];
...
bufferr[100] = 0; // Oops.
memcpy (buffer, NULL, 100); // Oops and... oops.

Most likely memcpy() in ReceiveData_GetLast() copies more than 120000
bytes
for some reason or uses invalid pointer(s).
Add some verification code to ReceiveData_GetLast() to verify array
boundaries/pointers and pop up an assert in case of a problem.
That would help you figure out what's wrong. Also, it's a good idea to add
some check and return an error if data appears to be incorrect.

You should pass buffer size to ReceiveData_GetLast() so it won't copy too
much:

UCHAR buffer[120000];
..
long sizeBuf=sizeof(buffer);
..

In ReceiveData_GetLast():

size = ... ; // Where it's coming from? Can it be wrong?
source = ... ; // Where it's coming from? Can it be wrong?

ASSERT (buffer != NULL);
ASSERT (source != NULL);
ASSERT (sizeBuf > size);

// consider adding check and return an error instead of crashing.
..
memcpy (buffer, source, size);

Best regards,

Ilya

This posting is provided "AS IS" with no warranties, and confers no
rights.

--------------------
Reply-To: "Rick" <[email protected]>
From: "Rick" <[email protected]>
Newsgroups: microsoft.public.windowsce.embedded.vc,microsoft.public.dotnet.framework.com
pactframework,microsoft.public.dotnet.languages.vb,microsoft.public.windowsc
e.embedded.vb
Followup-To: microsoft.public.windowsce.embedded.vc
Subject: HELP !! pb calling eVC++ DLL from VB.NET on compact framework
Date: Tue, 30 Nov 2004 11:18:06 +0100
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X-MSMail-Priority: Normal
X-Newsreader: Microsoft Outlook Express 6.00.2900.2180
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microsoft.public.windowsce.embedded.vb:21461
microsoft.public.windowsce.embedded.vc:36880
X-Tomcat-NG: microsoft.public.dotnet.framework.compactframework

hi all !

i need your HELP ! (it's long to explain but it's needed)

i have a big problem (for me) with my APP/DLL

i have made an Application with VB.NET for Compact framework that call an
DLL written in eVC++ 4.

the pb is i get a "First-chance exception ... Access violation" sometimes...

before my VB app are small (and i haven't the pb) but now is bigger (and
i
have the pb all the time).

when i debug the DLL, at the exception if i continu, i often get a "stack
overflow"..

i have read many things on the net but i haven't found a solution for the
pb. it seem its a limit of 4k(or 64k) boundary page pb with the stack..
here the start of my DLL function :

char __declspec(dllexport) f_com_ReadAcq(char voie,double * pValeurs, int
*nbValeur)
{
UCHAR buffer[120000];
long sizeBuf=0;

ReceiveData_GetLast(&tdReceiveMemory, buffer,500, RECEIVE_DATA_ACQ, voie
,&sizeBuf);
..
..
}

in ReceiveData_GetLast i do some memcpy to "buffer" and it's these memcpy
that do exception...i have try to replace the memcpy by a soft loop then it
crash at same time..

the DLL function is called from many place on the vb.net app then in one
case (always the same) it work...

when it work, the &buffer = 0x2207F2CC
when it crash the &buffer = 0x22011f8c
when it crash the pointer to buffer = 0x22012000

i mean it's the 1FFF to 2000 boudary that cause crash...(4k page ??)

i mean i can use malloc to allocate my 120k buffer, but i'm afraid for
the
rest of development...if i have only 116 bytes of local memory available
(0x22012000 - 0x22011f8c)...then this problem can appairs later in
development even if i make all array with malloc............

can it be VB.NET that fill the stack ?and how i can do to "free" some bytes
of the stack before calling DLL...?

thank a lot for all people that can help me....(i'm on this pb since 3 days
now and my app is not finished.....)

Eric BOUXIROT
(sorry for my bad english)

you can answer me at (e-mail address removed)
Click to expand...
Click to expand...
 
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