linux-kernel - [PATCH 4/4] misc: xilinx_sdfec: Prevent integer overflow in xsdfec_table

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Date:   Wed, 21 Aug 2019 10:11:22 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Derek Kiernan <derek.kiernan@...inx.com>,
        Dragan Cvetic <dragan.cvetic@...inx.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Michal Simek <michal.simek@...inx.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: [PATCH 4/4] misc: xilinx_sdfec: Prevent integer overflow in
 xsdfec_table_write()

The checking here needs to handle integer overflows because "offset" and
"len" come from the user.

Fixes: 20ec628e8007 ("misc: xilinx_sdfec: Add ability to configure LDPC")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
---
 drivers/misc/xilinx_sdfec.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/xilinx_sdfec.c b/drivers/misc/xilinx_sdfec.c
index 3fc53d20abf3..0bf3bcc8e1ef 100644
--- a/drivers/misc/xilinx_sdfec.c
+++ b/drivers/misc/xilinx_sdfec.c
@@ -611,7 +611,9 @@ static int xsdfec_table_write(struct xsdfec_dev *xsdfec, u32 offset,
 	 * Writes that go beyond the length of
 	 * Shared Scale(SC) table should fail
 	 */
-	if ((XSDFEC_REG_WIDTH_JUMP * (offset + len)) > depth) {
+	if (offset > depth / XSDFEC_REG_WIDTH_JUMP ||
+	    len > depth / XSDFEC_REG_WIDTH_JUMP ||
+	    offset + len > depth / XSDFEC_REG_WIDTH_JUMP) {
 		dev_dbg(xsdfec->dev, "Write exceeds SC table length");
 		return -EINVAL;
 	}
-- 
2.20.1