LU-12101 socklnd: fix infinite loop in ksocknal_push()

If the list_for_each_entry() loop in ksocknal_push()
ever finds a match, then it will increment 'i', and the outer
loop will continue.

Once peer_off becomes larger than the number of matches
in a given chain, 'peer_ni' will be an invalid pointer, and
ksocknal_push_peer() will probably crash when called on it.

To abort the outer loop properly, we need to test if
"i <= peer_off", which indicates that all patching peers
have been found.

This bug can easily be reproduced by running
  lctl --net tcp push

Signed-off-by: Mr NeilBrown <[email protected]>
Change-Id: I9468214c7e1a0154213586cac0deb61afaa1d53d
Reviewed-on: https://review.whamcloud.com/34499
Tested-by: jenkins <[email protected]>
Tested-by: Maloo <[email protected]>
Reviewed-by: James Simmons <[email protected]>
Reviewed-by: Sonia Sharma <[email protected]>
Reviewed-by: Oleg Drokin <[email protected]>

Author: NeilBrown

lnet/klnds/socklnd/socklnd.c

@@ -1936,7 +1936,7 @@ ksocknal_push(struct lnet_ni *ni, struct lnet_process_id id)
 			}
 			read_unlock(&ksocknal_data.ksnd_global_lock);
 
-			if (i == 0) /* no match */
+			if (i <= peer_off) /* no match */
 				break;
 
 			rc = 0;