[PATCH] taskstats: fix sk_buff size calculation

prepare_reply() adds GENL_HDRLEN to the payload (genlmsg_total_size()),
but then it does genlmsg_put()->nlmsg_put(). This means we forget to
reserve a room for 'struct nlmsghdr'.

Signed-off-by: Oleg Nesterov <[e-mail]>
Cc: Thomas Graf <[e-mail]>
Cc: Andrew Morton <[e-mail]>
Cc: Shailabh Nagar <[e-mail]>
Cc: Balbir Singh <[e-mail]>
Cc: Jay Lan <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

kernel/taskstats.c

···
 	/*
 	 * If new attributes are added, please revisit this allocation
 	 */
-	skb = nlmsg_new(genlmsg_total_size(size), GFP_KERNEL);
+	size = nlmsg_total_size(genlmsg_total_size(size));
+	skb = nlmsg_new(size, GFP_KERNEL);
 	if (!skb)
 		return -ENOMEM;