drivers/hwspinlock: fix race between radix tree insertion and lookup
authorMatthew Wilcox <willy@linux.intel.com>
Wed, 3 Feb 2016 00:57:55 +0000 (16:57 -0800)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Thu, 25 Feb 2016 20:01:23 +0000 (12:01 -0800)
commit077b6173a8c89d666a06203f42267ff8b6d02d73
tree436055b69d5506cfc4990a94d4251f4bd517dd90
parentf4595e0081495b677a98c780e9ec1ab68ce89488
drivers/hwspinlock: fix race between radix tree insertion and lookup

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>
drivers/hwspinlock/hwspinlock_core.c