[PATCH AUTOSEL for 4.14 109/161] IB/hfi1: Fix for potential refcount leak in hfi1_open_file()

[Sasha Levin]

From: Alex Estrin <alex.est...@intel.com>

[ Upstream commit 2b1e7fe16124e86ee9242aeeee859c79a843e3a2 ]

The dd refcount is speculatively incremented prior to allocating
the fd memory with kzalloc(). If that kzalloc() failed the dd
refcount leaks.
Increment refcount on kzalloc success.

Fixes: e11ffbd57520 ("IB/hfi1: Do not free hfi1 cdev parent structure early")
Reviewed-by: Michael J Ruhl <michael.j.r...@intel.com>
Signed-off-by: Alex Estrin <alex.est...@intel.com>
Signed-off-by: Jason Gunthorpe <j...@mellanox.com>
Signed-off-by: Sasha Levin <alexander.le...@microsoft.com>
---
 drivers/infiniband/hw/hfi1/file_ops.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/infiniband/hw/hfi1/file_ops.c 
b/drivers/infiniband/hw/hfi1/file_ops.c
index fd28f09b4445..ee2253d06984 100644
--- a/drivers/infiniband/hw/hfi1/file_ops.c
+++ b/drivers/infiniband/hw/hfi1/file_ops.c
@@ -191,9 +191,6 @@ static int hfi1_file_open(struct inode *inode, struct file 
*fp)
        if (!atomic_inc_not_zero(&dd->user_refcount))
                return -ENXIO;
 
-       /* Just take a ref now. Not all opens result in a context assign */
-       kobject_get(&dd->kobj);
-
        /* The real work is performed later in assign_ctxt() */
 
        fd = kzalloc(sizeof(*fd), GFP_KERNEL);
@@ -203,6 +200,7 @@ static int hfi1_file_open(struct inode *inode, struct file 
*fp)
                fd->mm = current->mm;
                mmgrab(fd->mm);
                fd->dd = dd;
+               kobject_get(&fd->dd->kobj);
                fp->private_data = fd;
        } else {
                fp->private_data = NULL;
-- 
2.15.1