kernel_wait4()/kernel_waitid(): delay copying status to userland

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 8 insertions, 12 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index d44f12948c5f..94cdccf8e7e7 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1002,7 +1002,7 @@ struct wait_opts {
         struct pid              *wo_pid;
 
         struct siginfo __user   *wo_info;
-        int __user              *wo_stat;
+        int                     wo_stat;
         struct rusage           *wo_rusage;
 
         wait_queue_t            child_wait;
@@ -1189,8 +1189,7 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
         retval = 0;
         status = (p->signal->flags & SIGNAL_GROUP_EXIT)
                 ? p->signal->group_exit_code : p->exit_code;
-        if (!retval && wo->wo_stat)
-                retval = put_user(status, wo->wo_stat);
+        wo->wo_stat = status;
 
         infop = wo->wo_info;
         if (!retval && infop)
@@ -1322,8 +1321,7 @@ unlock_sig:
         if (wo->wo_rusage)
                 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
         retval = 0;
-        if (!retval && wo->wo_stat)
-                retval = put_user((exit_code << 8) | 0x7f, wo->wo_stat);
+        wo->wo_stat = (exit_code << 8) | 0x7f;
 
         infop = wo->wo_info;
         if (!retval && infop)
@@ -1383,12 +1381,9 @@ static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
         if (!wo->wo_info) {
                 if (wo->wo_rusage)
                         getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
-                retval = 0;
                 put_task_struct(p);
-                if (!retval && wo->wo_stat)
-                        retval = put_user(0xffff, wo->wo_stat);
-                if (!retval)
-                        retval = pid;
+                wo->wo_stat = 0xffff;
+                retval = pid;
         } else {
                 retval = wait_noreap_copyout(wo, p, pid, uid,
                                              CLD_CONTINUED, SIGCONT);
@@ -1662,7 +1657,6 @@ static long kernel_waitid(int which, pid_t upid, struct siginfo __user *infop,
         wo.wo_pid       = pid;
         wo.wo_flags     = options;
         wo.wo_info      = infop;
-        wo.wo_stat      = NULL;
         wo.wo_rusage    = ru;
         ret = do_wait(&wo);
 
@@ -1734,10 +1728,12 @@ static long kernel_wait4(pid_t upid, int __user *stat_addr,
         wo.wo_pid       = pid;
         wo.wo_flags     = options | WEXITED;
         wo.wo_info      = NULL;
-        wo.wo_stat      = stat_addr;
+        wo.wo_stat      = 0;
         wo.wo_rusage    = ru;
         ret = do_wait(&wo);
         put_pid(pid);
+        if (ret > 0 && stat_addr && put_user(wo.wo_stat, stat_addr))
+                ret = -EFAULT;
 
         return ret;
 }