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authorMatthew Wilcox <willy@linux.intel.com>2016-02-02 16:57:55 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2016-02-03 08:28:43 -0800
commitc6400ba7e13a41539342f1b6e1f9e78419cb0148 (patch)
tree4ac7cac19e5d9cfc275a7d99f11ea21026f20275
parent46437f9a554fbe3e110580ca08ab703b59f2f95a (diff)
downloadlinux-c6400ba7e13a41539342f1b6e1f9e78419cb0148.tar.bz2
drivers/hwspinlock: fix race between radix tree insertion and lookup
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@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ohad Ben-Cohen <ohad@wizery.com> Cc: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--drivers/hwspinlock/hwspinlock_core.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/hwspinlock/hwspinlock_core.c b/drivers/hwspinlock/hwspinlock_core.c
index 52f708bcf77f..d50c701b19d6 100644
--- a/drivers/hwspinlock/hwspinlock_core.c
+++ b/drivers/hwspinlock/hwspinlock_core.c
@@ -313,6 +313,10 @@ int of_hwspin_lock_get_id(struct device_node *np, int index)
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;