[PATCH 3.16 160/366] RDMA/ucma: ucma_context reference leak in error path

[Ben Hutchings]

3.16.60-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Shamir Rabinovitch <shamir.rabinovitch@xxxxxxxxxx>

commit ef95a90ae6f4f21990e1f7ced6719784a409e811 upstream.

Validating input parameters should be done before getting the cm_id
otherwise it can leak a cm_id reference.

Fixes: 6a21dfc0d0db ("RDMA/ucma: Limit possible option size")
Signed-off-by: Shamir Rabinovitch <shamir.rabinovitch@xxxxxxxxxx>
Reviewed-by: Leon Romanovsky <leonro@xxxxxxxxxxxx>
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/infiniband/core/ucma.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/infiniband/core/ucma.c
+++ b/drivers/infiniband/core/ucma.c
@@ -1204,13 +1204,13 @@ static ssize_t ucma_set_option(struct uc
 	if (copy_from_user(&cmd, inbuf, sizeof(cmd)))
 		return -EFAULT;
 
+	if (unlikely(cmd.optlen > KMALLOC_MAX_SIZE))
+		return -EINVAL;
+
 	ctx = ucma_get_ctx(file, cmd.id);
 	if (IS_ERR(ctx))
 		return PTR_ERR(ctx);
 
-	if (unlikely(cmd.optlen > KMALLOC_MAX_SIZE))
-		return -EINVAL;
-
 	optval = memdup_user((void __user *) (unsigned long) cmd.optval,
 			     cmd.optlen);
 	if (IS_ERR(optval)) {