linux-kernel - [PATCH] RDMA/cxgb3: Fix unintended sign extension

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Message-Id: <20181025143131.4048-1-colin.king@canonical.com>
Date:   Thu, 25 Oct 2018 15:31:31 +0100
From:   Colin King <colin.king@...onical.com>
To:     Steve Wise <swise@...lsio.com>, Doug Ledford <dledford@...hat.com>,
        Jason Gunthorpe <jgg@...pe.ca>, linux-rdma@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] RDMA/cxgb3: Fix unintended sign extension

From: Colin Ian King <colin.king@...onical.com>

In the expression "utx_len << 28", utx_len starts as u8, but is promoted
to a signed int, then sign-extended to u64.  If utx_len is 0xf8 or greater
then the sign extension will set all the upper bits of utx_cmd which is
probably not what was intended.  Cast to utx_len to u64  to avoid the sign
extension.

Detected by CoverityScan, CID#138764 ("Unintended sign extension")

Fixes: b038ced7b370 ("RDMA/cxgb3: Add driver for Chelsio T3 RNIC")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 drivers/infiniband/hw/cxgb3/cxio_hal.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/infiniband/hw/cxgb3/cxio_hal.c b/drivers/infiniband/hw/cxgb3/cxio_hal.c
index dcb4bba522ba..c5cb80ccc6d6 100644
--- a/drivers/infiniband/hw/cxgb3/cxio_hal.c
+++ b/drivers/infiniband/hw/cxgb3/cxio_hal.c
@@ -647,7 +647,7 @@ static int cxio_hal_ctrl_qp_write_mem(struct cxio_rdev *rdev_p, u32 addr,
 		wqe += (sizeof(struct t3_bypass_wr) >> 3);
 		utx_cmd = (T3_UTX_MEM_WRITE << 28) | (addr + i * 3);
 		utx_cmd <<= 32;
-		utx_cmd |= (utx_len << 28) | ((utx_len << 2) + 1);
+		utx_cmd |= ((u64)utx_len << 28) | ((utx_len << 2) + 1);
 		*wqe = cpu_to_be64(utx_cmd);
 		wqe++;
 		copy_data = (u8 *) data + i * 96;
-- 
2.19.1