radix-tree: Fix UBSAN warning
get_slot_offset() can be called with a NULL 'parent' argument.
In this case, the calculated value will not be used, but calculating
it is undefined. Rather than fixing the caller (__radix_tree_delete)
to not call get_slot_offset(), make get_slot_offset() robust against
being called with a NULL parent.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index a9e41ae..cc6096b 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -120,7 +120,7 @@ bool is_sibling_entry(const struct radix_tree_node *parent, void *node)
static inline unsigned long
get_slot_offset(const struct radix_tree_node *parent, void __rcu **slot)
{
- return slot - parent->slots;
+ return parent ? slot - parent->slots : 0;
}
static unsigned int radix_tree_descend(const struct radix_tree_node *parent,