Intercept linux2.4.20-8 and the system crashes when calling the function write.

During the interception of the write function of the linux2.4.20-8 system, the system crashes. For details, refer to Linux general technology-Linux programming and kernel information. If you replace write with mkdir, everything is normal, and mkdir becomes a null operation.
Source code:
# Ifndef MODULE
# Define MODULE
# Endif
# Ifndef _ KERNEL __
# Define _ KERNEL __
# Endif
# Include
# Include
# Include
# Include
# Include
# Include
# Include
# Include

MODULE_LICENSE ("GPL ");


Int ** sys_call_table = (int **) 0xc030a0f0;/* sys_call_table is exported, so we can access it */
Static unsigned long orig_write; // (int fd, char * buf, size_t count );


Int hacked_write (int fd, char * buf, size_t count)
{

Return 0;/* everything is OK, but he new systemcall does nothing */
}
Int init_module (void)/* module setup */
{
Orig_write = sys_call_table [SYS_write];
Sys_call_table [SYS_write] = hacked_write;
Return 0;
}
Void cleanup_module (void)/* module shutdown */
{
Sys_call_table [SYS_write] = orig_write;/* set mkdir syscall to the origal one */
}