RDMA/cma: Fix unbalanced cm_id reference count during address resolve
authorParav Pandit <parav@mellanox.com>
Sun, 26 Jan 2020 14:26:46 +0000 (16:26 +0200)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Fri, 14 Feb 2020 21:34:08 +0000 (16:34 -0500)
commit56b22525ab803752197a64baddf1cb927a424937
treeba8d0f91daba7571665a91d99a70d2db29e80722
parentb73401025a14b11f229526af4e799fa796284fe6
RDMA/cma: Fix unbalanced cm_id reference count during address resolve

commit b4fb4cc5ba83b20dae13cef116c33648e81d2f44 upstream.

Below commit missed the AF_IB and loopback code flow in
rdma_resolve_addr().  This leads to an unbalanced cm_id refcount in
cma_work_handler() which puts the refcount which was not incremented prior
to queuing the work.

A call trace is observed with such code flow:

 BUG: unable to handle kernel NULL pointer dereference at (null)
 [<ffffffff96b67e16>] __mutex_lock_slowpath+0x166/0x1d0
 [<ffffffff96b6715f>] mutex_lock+0x1f/0x2f
 [<ffffffffc0beabb5>] cma_work_handler+0x25/0xa0
 [<ffffffff964b9ebf>] process_one_work+0x17f/0x440
 [<ffffffff964baf56>] worker_thread+0x126/0x3c0

Hence, hold the cm_id reference when scheduling the resolve work item.

Fixes: 722c7b2bfead ("RDMA/{cma, core}: Avoid callback on rdma_addr_cancel()")
Link: https://lore.kernel.org/r/20200126142652.104803-2-leon@kernel.org
Signed-off-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/infiniband/core/cma.c