From: Sean Hefty Date: Wed, 23 Feb 2011 16:17:40 +0000 (-0800) Subject: IB/cm: Bump reference count on cm_id before invoking callback X-Git-Tag: v2.6.38.1~68 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=6fee8c663b4c7253b4ee68ae2680c8c4cb25a986;p=karo-tx-linux.git IB/cm: Bump reference count on cm_id before invoking callback 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 Acked-by: Doug Ledford Signed-off-by: Roland Dreier Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/infiniband/core/cm.c b/drivers/infiniband/core/cm.c index 64e0903091a8..1d9616be4192 100644 --- a/drivers/infiniband/core/cm.c +++ b/drivers/infiniband/core/cm.c @@ -2989,6 +2989,7 @@ static int cm_sidr_req_handler(struct cm_work *work) 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;