From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Wed, 21 Aug 2019 07:11:22 +0000 (+0300)
Subject: misc: xilinx_sdfec: Prevent integer overflow in xsdfec_table_write()
X-Git-Tag: for-linus-2019-09-27~93^2~54
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=6123f1fe53985645992b2ff648b3087b77b3ed16;p=linux-2.6-block.git

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@oracle.com>
Reviewed-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Dragan Cvetic <dragan.cvetic@xilinx.com>
Link: https://lore.kernel.org/r/20190821071122.GD26957@mwanda
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

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;
 	}