osf_wait4: switch to kernel_wait4()

... and sanitize copying rusage to userland
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/alpha/kernel/osf_sys.c

@@ -1183,48 +1183,23 @@ SYSCALL_DEFINE2(osf_getrusage, int, who, struct rusage32 __user *, ru)
 SYSCALL_DEFINE4(osf_wait4, pid_t, pid, int __user *, ustatus, int, options,
 		struct rusage32 __user *, ur)
 {
-	struct rusage r;
-	long ret, err;
 	unsigned int status = 0;
-	mm_segment_t old_fs;
-
+	struct rusage r;
+	long err = kernel_wait4(pid, &status, options, &r);
+	if (err <= 0)
+		return err;
+	if (put_user(status, ustatus))
+		return -EFAULT;
 	if (!ur)
-		return sys_wait4(pid, ustatus, options, NULL);
-
-	old_fs = get_fs();
-		
-	set_fs (KERNEL_DS);
-	ret = sys_wait4(pid, (unsigned int __user *) &status, options,
-			(struct rusage __user *) &r);
-	set_fs (old_fs);
-
-	if (!access_ok(VERIFY_WRITE, ur, sizeof(*ur)))
+		return err;
+	if (put_tv32(&ur->ru_utime, &r.ru_utime))
 		return -EFAULT;
-
-	err = put_user(status, ustatus);
-	if (ret < 0)
-		return err ? err : ret;
-
-	err |= __put_user(r.ru_utime.tv_sec, &ur->ru_utime.tv_sec);
-	err |= __put_user(r.ru_utime.tv_usec, &ur->ru_utime.tv_usec);
-	err |= __put_user(r.ru_stime.tv_sec, &ur->ru_stime.tv_sec);
-	err |= __put_user(r.ru_stime.tv_usec, &ur->ru_stime.tv_usec);
-	err |= __put_user(r.ru_maxrss, &ur->ru_maxrss);
-	err |= __put_user(r.ru_ixrss, &ur->ru_ixrss);
-	err |= __put_user(r.ru_idrss, &ur->ru_idrss);
-	err |= __put_user(r.ru_isrss, &ur->ru_isrss);
-	err |= __put_user(r.ru_minflt, &ur->ru_minflt);
-	err |= __put_user(r.ru_majflt, &ur->ru_majflt);
-	err |= __put_user(r.ru_nswap, &ur->ru_nswap);
-	err |= __put_user(r.ru_inblock, &ur->ru_inblock);
-	err |= __put_user(r.ru_oublock, &ur->ru_oublock);
-	err |= __put_user(r.ru_msgsnd, &ur->ru_msgsnd);
-	err |= __put_user(r.ru_msgrcv, &ur->ru_msgrcv);
-	err |= __put_user(r.ru_nsignals, &ur->ru_nsignals);
-	err |= __put_user(r.ru_nvcsw, &ur->ru_nvcsw);
-	err |= __put_user(r.ru_nivcsw, &ur->ru_nivcsw);
-
-	return err ? err : ret;
+	if (put_tv32(&ur->ru_stime, &r.ru_stime))
+		return -EFAULT;
+	if (copy_to_user(&ur->ru_maxrss, &r.ru_maxrss,
+	      sizeof(struct rusage32) - offsetof(struct rusage32, ru_maxrss)))
+		return -EFAULT;
+	return err;
 }
 
 /*

include/linux/sched/task.h

@@ -9,6 +9,7 @@
 #include <linux/sched.h>
 
 struct task_struct;
+struct rusage;
 union thread_union;
 
 /*
@@ -74,6 +75,7 @@ extern long _do_fork(unsigned long, unsigned long, unsigned long, int __user *,
 extern long do_fork(unsigned long, unsigned long, unsigned long, int __user *, int __user *);
 struct task_struct *fork_idle(int);
 extern pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
+extern long kernel_wait4(pid_t, int *, int, struct rusage *);
 
 extern void free_task(struct task_struct *tsk);
 

kernel/exit.c

@@ -1639,8 +1639,8 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
 	return -EFAULT;
 }
 
-static long kernel_wait4(pid_t upid, int __user *stat_addr,
-			int options, struct rusage *ru)
+long kernel_wait4(pid_t upid, int __user *stat_addr, int options,
+		  struct rusage *ru)
 {
 	struct wait_opts wo;
 	struct pid *pid = NULL;