Created attachment 182207 [details]
patch for linux_sys_futex()

In linux compat layer, the syscall futex does not handle FUTEX_WAKE_OP well when using the same address for arguments uaddr and uaddr2. 

The following linux program can result in kernel panic.

#define _GNU_SOURCE
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/wait.h>
#include <sys/mman.h>
#include <sys/syscall.h>

#include <linux/futex.h>
#include <sys/time.h>

static int
futex(int *uaddr, int futex_op, int val,
		int val2, int *uaddr2, int val3)
{
	return syscall(SYS_futex, uaddr, futex_op, val,
			val2, uaddr, val3);
}

int main(void){
	int ret;
	int addr;

	ret = futex(&addr, FUTEX_WAKE_OP, 1, 1, &addr, 2);
	printf("ret: %d\n", ret);
}