lkml.org 
[lkml]   [2008]   [Sep]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
DateThu, 18 Sep 2008 14:30:12 +0200
Fromevilsocket <>
SubjectStack buffer size issue
Hello to all, i'm trying to develop a kernel module that accepts an 
ioctl with this structure :

typedef struct{
/* [INPUT] */
long process;
unsigned long address;
/* [OUTPUT] */
long mm_size;
}
mg_query_t;
where :

process : is the pid of a process .
address : is the address of a buffer on the stack of that process .

mm_size : *should* be the return value of the ioctl, indicating the size
of that buffer, as an example (userspace test application):

char * abuffer[123];
mg_query_t query;

query.process = getpid();
query.address = abuffer;

if( ioctl( fd, IOCTL_MTABLE_BY_PID, &query ) < 0 ){
close(fd);
perror( "IOCTL_MTABLE_BY_PID" );
return -1;
}
printf( "SIZE : %d\n", query.mm_size );



This *should* give the output :

SIZE : 123

I'm using the struct task_struct in the kernel module, looping the mmap
to find the vm area the address resides in and then to set

mm_size = vm_end - vm_start

But doing so i obtaing only the size of the vm page the buffer resides .

Any hints ?

Thanks in advantage .


\
 
 \ /
  Last update: 2008-09-18 14:33    [from the cache]
©2003-2010