4.4-stable review patch. If anyone has any objections, please let me know.
------------------ From: Matthew Wilcox <[email protected]> commit c6400ba7e13a41539342f1b6e1f9e78419cb0148 upstream. of_hwspin_lock_get_id() is protected by the RCU lock, which means that insertions can occur simultaneously with the lookup. If the radix tree transitions from a height of 0, we can see a slot with the indirect_ptr bit set, which will cause us to at least read random memory, and could cause other havoc. Fix this by using the newly introduced radix_tree_iter_retry(). Signed-off-by: Matthew Wilcox <[email protected]> Cc: Hugh Dickins <[email protected]> Cc: Ohad Ben-Cohen <[email protected]> Cc: Konstantin Khlebnikov <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- drivers/hwspinlock/hwspinlock_core.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/drivers/hwspinlock/hwspinlock_core.c +++ b/drivers/hwspinlock/hwspinlock_core.c @@ -313,6 +313,10 @@ int of_hwspin_lock_get_id(struct device_ hwlock = radix_tree_deref_slot(slot); if (unlikely(!hwlock)) continue; + if (radix_tree_is_indirect_ptr(hwlock)) { + slot = radix_tree_iter_retry(&iter); + continue; + } if (hwlock->bank->dev->of_node == args.np) { ret = 0;
