From: Kent Overstreet <kent.overstreet@xxxxxxxxx>
[ Upstream commit b2f11c6f3e1fc60742673b8675c95b78447f3dae ]
If we need to increase the tree depth, allocate a new node, and then
race with another thread that increased the tree depth before us, we'll
still have a preallocated node that might be used later.
If we then use that node for a new non-root node, it'll still have a
pointer to the old root instead of being zeroed - fix this by zeroing it
in the cmpxchg failure path.
Signed-off-by: Kent Overstreet <kent.overstreet@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
lib/generic-radix-tree.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/lib/generic-radix-tree.c b/lib/generic-radix-tree.c
index f25eb111c0516..34d3ac52de894 100644
--- a/lib/generic-radix-tree.c
+++ b/lib/generic-radix-tree.c
@@ -131,6 +131,8 @@ void *__genradix_ptr_alloc(struct __genradix *radix, size_t offset,
if ((v = cmpxchg_release(&radix->root, r, new_root)) == r) {
v = new_root;
new_node = NULL;
+ } else {
+ new_node->children[0] = NULL;
}
}
--
2.43.0
