From 1ba95552a4efd2f9e779cd840ffbd159bd0e9c7f Mon Sep 17 00:00:00 2001 From: Patrick McHardy Date: Thu, 30 Aug 2012 07:01:30 +0000 Subject: [PATCH] IPoIB: Fix use-after-free of multicast object commit bea1e22df494a729978e7f2c54f7bda328f74bc3 upstream. Fix a crash in ipoib_mcast_join_task(). (with help from Or Gerlitz) Commit c8c2afe360b7 ("IPoIB: Use rtnl lock/unlock when changing device flags") added a call to rtnl_lock() in ipoib_mcast_join_task(), which is run from the ipoib_workqueue, and hence the workqueue can't be flushed from the context of ipoib_stop(). In the current code, ipoib_stop() (which doesn't flush the workqueue) calls ipoib_mcast_dev_flush(), which goes and deletes all the multicast entries. This takes place without any synchronization with a possible running instance of ipoib_mcast_join_task() for the same ipoib device, leading to a crash due to NULL pointer dereference. Fix this by making sure that the workqueue is flushed before ipoib_mcast_dev_flush() is called. To make that possible, we move the RTNL-lock wrapped code to ipoib_mcast_join_finish(). Signed-off-by: Patrick McHardy Signed-off-by: Roland Dreier Signed-off-by: Ben Hutchings --- Reading git-format-patch failed