From patchwork series 498920

https://patchwork.ozlabs.org//project/linuxppc-dev/list/?series=498920

Author: Fox Snowpatch

arch/powerpc/platforms/pseries/pseries_energy.c

@@ -184,6 +184,7 @@ static int drc_index_to_cpu(u32 drc_index)
 #define FLAGS_MODE1	0x004E200000080E01UL
 #define FLAGS_MODE2	0x004E200000080401UL
 #define FLAGS_ACTIVATE  0x100
+#define BEST_ENERGY_LIST_MAX_ENTRIES	(PAGE_SIZE / (sizeof(u32) * 2))
 
 static ssize_t get_best_energy_list(char *page, int activate)
 {
@@ -208,6 +209,11 @@ static ssize_t get_best_energy_list(char *page, int activate)
 		return -EINVAL;
 	}
 
+	if (retbuf[0] > BEST_ENERGY_LIST_MAX_ENTRIES) {
+		free_page((unsigned long)buf_page);
+		return -EINVAL;
+	}
+
 	cnt = retbuf[0];
 	for (i = 0; i < cnt; i++) {
 		cpu = drc_index_to_cpu(buf_page[2*i+1]);