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drivers/hwspinlock: fix race between radix tree insertion and lookup

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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@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ohad Ben-Cohen <ohad@wizery.com>
Cc: Konstantin Khlebnikov <khlebnikov@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Matthew Wilcox 2016-02-02 16:57:55 -08:00 • committed by Greg Kroah-Hartman
parent f4595e0081
commit 077b6173a8
1 changed files with 4 additions and 0 deletions
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4
drivers/hwspinlock/hwspinlock_core.c
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@ -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;