From 294c149a209c6196c2de85f512b52ef50f519949 Mon Sep 17 00:00:00 2001

From: Dan Carpenter <dan.carpenter@oracle.com>

Date: Fri, 1 Feb 2019 11:28:16 +0300

Subject: [Backport 294c149a209c] skge: potential memory corruption in

 skge_get_regs()

The "p" buffer is 0x4000 bytes long.  B3_RI_WTO_R1 is 0x190.  The value

of "regs->len" is in the 1-0x4000 range.  The bug here is that

"regs->len - B3_RI_WTO_R1" can be a negative value which would lead to

memory corruption and an abrupt crash.

Fixes: c3f8be961808 ("[PATCH] skge: expand ethtool debug register dump")

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

Signed-off-by: David S. Miller <davem@davemloft.net>

---

 src/skge.c | 6 ++++--

 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/skge.c b/src/skge.c

index 04fd1f135011f1a068bbc79991af0d05a7c56583..654ac534b10e3e8e04911b618d5fd1cb6fb5c8c8 100644

--- a/src/skge.c

+++ b/src/skge.c

@@ -152,8 +152,10 @@ static void skge_get_regs(struct net_device *dev, struct ethtool_regs *regs,

 	memset(p, 0, regs->len);

 	memcpy_fromio(p, io, B3_RAM_ADDR);

-	memcpy_fromio(p + B3_RI_WTO_R1, io + B3_RI_WTO_R1,

-		      regs->len - B3_RI_WTO_R1);

+	if (regs->len > B3_RI_WTO_R1) {

+		memcpy_fromio(p + B3_RI_WTO_R1, io + B3_RI_WTO_R1,

+			      regs->len - B3_RI_WTO_R1);

+	}

 }

 /* Wake on Lan only supported on Yukon chips with rev 1 or above */

-- 

2.31.1