[bug report] seccomp: Add find_notification helper

[Dan Carpenter <dan.carpenter@oracle.com>]

[ Kees, why am I getting tons and tons of these warnings?  Are we not
  going to initialize things manually any more? ]

Hello Sargun Dhillon,

The patch 186f03857c48: "seccomp: Add find_notification helper" from
Jun 1, 2020, leads to the following static checker warning:

	kernel/seccomp.c:1124 seccomp_notify_recv()
	error: uninitialized symbol 'knotif'.

kernel/seccomp.c
  1091  static long seccomp_notify_recv(struct seccomp_filter *filter,
  1092                                  void __user *buf)
  1093  {
  1094          struct seccomp_knotif *knotif, *cur;
                                       ^^^^^^
This used to be initialized to NULL here.

  1095          struct seccomp_notif unotif;
  1096          ssize_t ret;
  1097  
  1098          /* Verify that we're not given garbage to keep struct extensible. */
  1099          ret = check_zeroed_user(buf, sizeof(unotif));
  1100          if (ret < 0)
  1101                  return ret;
  1102          if (!ret)
  1103                  return -EINVAL;
  1104  
  1105          memset(&unotif, 0, sizeof(unotif));
  1106  
  1107          ret = down_interruptible(&filter->notif->request);
  1108          if (ret < 0)
  1109                  return ret;
  1110  
  1111          mutex_lock(&filter->notify_lock);
  1112          list_for_each_entry(cur, &filter->notif->notifications, list) {
  1113                  if (cur->state == SECCOMP_NOTIFY_INIT) {
  1114                          knotif = cur;
                                ^^^^^^^^^^^^

  1115                          break;
  1116                  }
  1117          }
  1118  
  1119          /*
  1120           * If we didn't find a notification, it could be that the task was
  1121           * interrupted by a fatal signal between the time we were woken and
  1122           * when we were able to acquire the rw lock.
  1123           */
  1124          if (!knotif) {
                     ^^^^^^
But now it's uninitialized.

  1125                  ret = -ENOENT;
  1126                  goto out;
  1127          }
  1128  
  1129          unotif.id = knotif->id;

regards,
dan carpenter