Subject: [PATCH 4/4] misc: xilinx_sdfec: Prevent integer overflow in xsdfec_table_write()

From: Dan Carpenter <[email-masked]>
Date: Wed, 21 Aug 2019 10:11:22 +0300

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 <[email-masked]>
---
 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

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