diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index 292ebc7fe4d0ac0261f1c0fc2906cc045860867b..66fd5bd78318b36c247593d45205001303d2a1bf 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -1198,6 +1198,9 @@ static int __init parse_memmap_opt(char *p)
 	char *oldp;
 	u64 start_at, mem_size;
 
+	if (!p)
+		return -EINVAL;
+
 	if (!strcmp(p, "exactmap")) {
 #ifdef CONFIG_CRASH_DUMP
 		/*