[PATCH 4.19 37/57] ravb: Fix use-after-free ravb_tstamp_skb

Greg Kroah-Hartman
2019-09-08T12:49:14Z

[ Upstream commit cfef46d692efd852a0da6803f920cc756eea2855 ]

When a Tx timestamp is requested, a pointer to the skb is stored in the
ravb_tstamp_skb struct. This was done without an skb_get. There exists
the possibility that the skb could be freed by ravb_tx_free (when
ravb_tx_free is called from ravb_start_xmit) before the timestamp was
processed, leading to a use-after-free bug.

Use skb_get when filling a ravb_tstamp_skb struct, and add appropriate
frees/consumes when a ravb_tstamp_skb struct is freed.

Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper")
Signed-off-by: Tho Vu <tho.vu.wh@rvc.renesas.com>
Signed-off-by: Kazuya Mizuguchi <kazuya.mizuguchi.ks@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/renesas/ravb_main.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index 5f092bbd05148..5462d2e8a1b71 100644
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c
@@ -1,7 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
/* Renesas Ethernet AVB device driver
*
- * Copyright (C) 2014-2015 Renesas Electronics Corporation
+ * Copyright (C) 2014-2019 Renesas Electronics Corporation
* Copyright (C) 2015 Renesas Solutions Corp.
* Copyright (C) 2015-2016 Cogent Embedded, Inc. <source@cogentembedded.com>
*
@@ -514,7 +514,10 @@ static void ravb_get_tx_tstamp(struct net_device *ndev)
kfree(ts_skb);
if (tag == tfa_tag) {
skb_tstamp_tx(skb, &shhwtstamps);
+ dev_consume_skb_any(skb);
break;
+ } else {
+ dev_kfree_skb_any(skb);
}
}
ravb_modify(ndev, TCCR, TCCR_TFR, TCCR_TFR);
@@ -1556,7 +1559,7 @@ static netdev_tx_t ravb_start_xmit(struct sk_buff *skb, struct net_device *ndev)
DMA_TO_DEVICE);
goto unmap;
}
- ts_skb->skb = skb;
+ ts_skb->skb = skb_get(skb);
ts_skb->tag = priv->ts_skb_tag++;
priv->ts_skb_tag &= 0x3ff;
list_add_tail(&ts_skb->list, &priv->ts_skb_list);
@@ -1685,6 +1688,7 @@ static int ravb_close(struct net_device *ndev)
/* Clear the timestamp list */
list_for_each_entry_safe(ts_skb, ts_skb2, &priv->ts_skb_list, list) {
list_del(&ts_skb->list);
+ kfree_skb(ts_skb->skb);
kfree(ts_skb);
}

--
2.20.1