net: sysctl: do not reserve an extra char in dump_cpumask temporary buffer

When computing the length we'll be able to use out of the buffers, one
char is removed from the temporary one to make room for a newline. It
should be removed from the output buffer length too, but in reality this
is not needed as the later call to scnprintf makes sure a null char is
written at the end of the buffer which we override with the newline.

Signed-off-by: Antoine Tenart <atenart@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

net/core/sysctl_net_core.c

@@ -62,7 +62,7 @@ static void dump_cpumask(void *buffer, size_t *lenp, loff_t *ppos,
 		return;
 	}
 
-	len = min(sizeof(kbuf) - 1, *lenp);
+	len = min(sizeof(kbuf), *lenp);
 	len = scnprintf(kbuf, len, "%*pb", cpumask_pr_args(mask));
 	if (!len) {
 		*lenp = 0;