Messages in this thread |  | | | Date | Thu, 18 Sep 2008 14:30:12 +0200 | | From | evilsocket <> | | Subject | Stack buffer size issue |
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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 .
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