[PATCH 4.14 170/205] skge: potential memory corruption in skge_get_regs()

Greg Kroah-Hartman
2019-02-11T15:02:29Z

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

[ Upstream commit 294c149a209c6196c2de85f512b52ef50f519949 ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/ethernet/marvell/skge.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/net/ethernet/marvell/skge.c
+++ b/drivers/net/ethernet/marvell/skge.c
@@ -152,8 +152,10 @@ static void skge_get_regs(struct net_dev
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 */