Commit 35e691ed authored Dec 08, 2017 by Geert Uytterhoeven Committed by Rob Herring Dec 08, 2017

of: overlay: Fix out-of-bounds write in init_overlay_changeset()



If an overlay has no "__symbols__" node, but it has nodes without
"__overlay__" subnodes at the end (e.g. a "__fixups__" node), after
filling in all fragments for nodes with "__overlay__" subnodes,
"fragment = &fragments[cnt]" will point beyond the end of the allocated
array.

Hence writing to "fragment->overlay" will overwrite unallocated memory,
which may lead to a crash later.

Fix this by deferring both the assignment to "fragment" and the
offending write afterwards until we know for sure the node has an
"__overlay__" subnode, and thus a valid entry in "fragments[]".

Fixes: 61b4de4e ("of: overlay: minor restructuring")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Rob Herring <robh@kernel.org>

parent 5e474817

drivers/of/overlay.c

+4 −3

Original line number	Diff line number	Diff line
		@@ -572,9 +572,10 @@ static int init_overlay_changeset(struct overlay_changeset *ovcs,

		cnt = 0;
		for_each_child_of_node(tree, node) {
		overlay_node = of_get_child_by_name(node, "__overlay__");
		if (overlay_node) {
		fragment = &fragments[cnt];
		fragment->overlay = of_get_child_by_name(node, "__overlay__");
		if (fragment->overlay) {
		fragment->overlay = overlay_node;
		fragment->target = find_target_node(node);
		if (!fragment->target) {
		of_node_put(fragment->overlay);