x86/cpu: Fix overrun check in arch_print_cpu_modalias()

snprintf() does not return a negative value when truncating.
Signed-off-by: NBen Hutchings <ben@decadent.org.uk>
Acked-by: NThomas Renninger <trenn@suse.de>
Acked-by: NH. Peter Anvin <hpa@zytor.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/x86/kernel/cpu/match.c

@@ -67,7 +67,7 @@ ssize_t arch_print_cpu_modalias(struct device *dev,
 	for (i = 0; i < NCAPINTS*32; i++) {
 		if (boot_cpu_has(i)) {
 			n = snprintf(buf, size, ",%04X", i);
-			if (n < 0) {
+			if (n >= size) {
 				WARN(1, "x86 features overflow page\n");
 				break;
 			}