linux-kernel - [PATCH] IB/mlx4: prevent undefined shift in set_user_sq

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Date:   Sat, 8 Jun 2019 12:22:31 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Yishai Hadas <yishaih@...lanox.com>
Cc:     Doug Ledford <dledford@...hat.com>, Jason Gunthorpe <jgg@...pe.ca>,
        linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: [PATCH] IB/mlx4: prevent undefined shift in set_user_sq_size()

The ucmd->log_sq_bb_count is a u8 that comes from the user.  If it's
larger than the number of bits in an int then that's undefined behavior.
It turns out this doesn't really cause an issue at runtime but it's
still nice to clean it up.

Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
---
 drivers/infiniband/hw/mlx4/qp.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/hw/mlx4/qp.c b/drivers/infiniband/hw/mlx4/qp.c
index 5221c0794d1d..9f6eb23e8044 100644
--- a/drivers/infiniband/hw/mlx4/qp.c
+++ b/drivers/infiniband/hw/mlx4/qp.c
@@ -439,7 +439,8 @@ static int set_user_sq_size(struct mlx4_ib_dev *dev,
 			    struct mlx4_ib_create_qp *ucmd)
 {
 	/* Sanity check SQ size before proceeding */
-	if ((1 << ucmd->log_sq_bb_count) > dev->dev->caps.max_wqes	 ||
+	if (ucmd->log_sq_bb_count > 31					 ||
+	    (1 << ucmd->log_sq_bb_count) > dev->dev->caps.max_wqes	 ||
 	    ucmd->log_sq_stride >
 		ilog2(roundup_pow_of_two(dev->dev->caps.max_sq_desc_sz)) ||
 	    ucmd->log_sq_stride < MLX4_IB_MIN_SQ_STRIDE)
-- 
2.20.1