5.15-stable review patch. If anyone has any objections, please let me know.
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From: Kent Overstreet kent.overstreet@linux.dev
[ 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@linux.dev Signed-off-by: Sasha Levin sashal@kernel.org --- 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 f25eb111c051..34d3ac52de89 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; } }