| From 29963437a48475036353b95ab142bf199adb909e Mon Sep 17 00:00:00 2001 |
| From: Sean Hefty <sean.hefty@intel.com> |
| Date: Wed, 23 Feb 2011 08:17:40 -0800 |
| Subject: IB/cm: Bump reference count on cm_id before invoking callback |
| |
| From: Sean Hefty <sean.hefty@intel.com> |
| |
| commit 29963437a48475036353b95ab142bf199adb909e upstream. |
| |
| When processing a SIDR REQ, the ib_cm allocates a new cm_id. The |
| refcount of the cm_id is initialized to 1. However, cm_process_work |
| will decrement the refcount after invoking all callbacks. The result |
| is that the cm_id will end up with refcount set to 0 by the end of the |
| sidr req handler. |
| |
| If a user tries to destroy the cm_id, the destruction will proceed, |
| under the incorrect assumption that no other threads are referencing |
| the cm_id. This can lead to a crash when the cm callback thread tries |
| to access the cm_id. |
| |
| This problem was noticed as part of a larger investigation with kernel |
| crashes in the rdma_cm when running on a real time OS. |
| |
| Signed-off-by: Sean Hefty <sean.hefty@intel.com> |
| Acked-by: Doug Ledford <dledford@redhat.com> |
| Signed-off-by: Roland Dreier <roland@purestorage.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> |
| |
| --- |
| drivers/infiniband/core/cm.c | 1 + |
| 1 file changed, 1 insertion(+) |
| |
| --- a/drivers/infiniband/core/cm.c |
| +++ b/drivers/infiniband/core/cm.c |
| @@ -2986,6 +2986,7 @@ static int cm_sidr_req_handler(struct cm |
| goto out; /* No match. */ |
| } |
| atomic_inc(&cur_cm_id_priv->refcount); |
| + atomic_inc(&cm_id_priv->refcount); |
| spin_unlock_irq(&cm.lock); |
| |
| cm_id_priv->id.cm_handler = cur_cm_id_priv->id.cm_handler; |
