This is a note to let you know that I've just added the patch titled drivers/hwspinlock: fix race between radix tree insertion and lookup to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: drivers-hwspinlock-fix-race-between-radix-tree-insertion-and-lookup.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From c6400ba7e13a41539342f1b6e1f9e78419cb0148 Mon Sep 17 00:00:00 2001 From: Matthew Wilcox <willy@xxxxxxxxxxxxxxx> Date: Tue, 2 Feb 2016 16:57:55 -0800 Subject: drivers/hwspinlock: fix race between radix tree insertion and lookup From: Matthew Wilcox <willy@xxxxxxxxxxxxxxx> 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 <willy@xxxxxxxxxxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Cc: Ohad Ben-Cohen <ohad@xxxxxxxxxx> Cc: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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; Patches currently in stable-queue which might be from willy@xxxxxxxxxxxxxxx are queue-4.4/radix-tree-fix-oops-after-radix_tree_iter_retry.patch queue-4.4/drivers-hwspinlock-fix-race-between-radix-tree-insertion-and-lookup.patch queue-4.4/radix-tree-fix-race-in-gang-lookup.patch queue-4.4/devm_memremap_release-fix-memremap-d-addr-handling.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html