Index: sys/arch/arm/fdt/arm_simplefb.c
===================================================================
RCS file: /cvsroot/src/sys/arch/arm/fdt/arm_simplefb.c,v
retrieving revision 1.9
diff -u -p -r1.9 arm_simplefb.c
--- sys/arch/arm/fdt/arm_simplefb.c	2 Mar 2021 07:02:05 -0000	1.9
+++ sys/arch/arm/fdt/arm_simplefb.c	2 Mar 2021 13:22:35 -0000
@@ -237,7 +237,11 @@ arm_simplefb_preattach(void)
 		return;
 	}
 
-	if (size < width * height * depth)
+	if (stride < width * depth) {
+		return;
+	}
+
+	if (size < stride * height)
 		return;
 
 	if (bus_space_map(bst, addr, size,
Index: sys/dev/fdt/simplefb.c
===================================================================
RCS file: /cvsroot/src/sys/dev/fdt/simplefb.c,v
retrieving revision 1.13
diff -u -p -r1.13 simplefb.c
--- sys/dev/fdt/simplefb.c	2 Mar 2021 07:02:06 -0000	1.13
+++ sys/dev/fdt/simplefb.c	2 Mar 2021 13:22:35 -0000
@@ -169,7 +169,12 @@ simplefb_attach_genfb(struct simplefb_so
 		return ENXIO;
 	}
 
-	if (size < width * height * depth) {
+	if (stride < width * depth) {
+		aprint_error(": incorrect stride\n");
+		return ENXIO;
+	}
+
+	if (size < stride * height) {
 		aprint_error(": incorrect size\n");
 		return ENXIO;
 	}