netdev - [PATCH net 5/8] net: atlantic: fix use after free kasan warn

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Message-ID: <fd1ea53b6c8d421052c709554217a247f250b65b.1580299250.git.irusskikh@marvell.com>
Date:   Fri, 14 Feb 2020 18:44:55 +0300
From:   Igor Russkikh <irusskikh@...vell.com>
To:     <netdev@...r.kernel.org>
CC:     <dbogdanov@...vell.com>, <pbelous@...vell.com>,
        <ndanilov@...vell.com>, <davem@...emloft.net>,
        Igor Russkikh <irusskikh@...vell.com>
Subject: [PATCH net 5/8] net: atlantic: fix use after free kasan warn

From: Pavel Belous <pbelous@...vell.com>

skb->len is used to calculate statistics after xmit invocation.

Under a stress load it may happen that skb will be xmited,
rx interrupt will come and skb will be freed, all before xmit function
is even returned.

Eventually, skb->len will access unallocated area.

Moving stats calculation into tx_clean routine.

Fixes: 018423e90bee ("net: ethernet: aquantia: Add ring support code")
Reported-by: Christophe Vu-Brugier <cvubrugier@...tmail.fm>
Signed-off-by: Igor Russkikh <irusskikh@...vell.com>
Signed-off-by: Pavel Belous <pbelous@...vell.com>
Signed-off-by: Dmitry Bogdanov <dbogdanov@...vell.com>
---
 drivers/net/ethernet/aquantia/atlantic/aq_nic.c  | 4 ----
 drivers/net/ethernet/aquantia/atlantic/aq_ring.c | 7 +++++--
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/aquantia/atlantic/aq_nic.c b/drivers/net/ethernet/aquantia/atlantic/aq_nic.c
index c85e3e29012c..263beea1859c 100644
--- a/drivers/net/ethernet/aquantia/atlantic/aq_nic.c
+++ b/drivers/net/ethernet/aquantia/atlantic/aq_nic.c
@@ -655,10 +655,6 @@ int aq_nic_xmit(struct aq_nic_s *self, struct sk_buff *skb)
 	if (likely(frags)) {
 		err = self->aq_hw_ops->hw_ring_tx_xmit(self->aq_hw,
 						       ring, frags);
-		if (err >= 0) {
-			++ring->stats.tx.packets;
-			ring->stats.tx.bytes += skb->len;
-		}
 	} else {
 		err = NETDEV_TX_BUSY;
 	}
diff --git a/drivers/net/ethernet/aquantia/atlantic/aq_ring.c b/drivers/net/ethernet/aquantia/atlantic/aq_ring.c
index 6941999ae845..bae95a618560 100644
--- a/drivers/net/ethernet/aquantia/atlantic/aq_ring.c
+++ b/drivers/net/ethernet/aquantia/atlantic/aq_ring.c
@@ -272,9 +272,12 @@ bool aq_ring_tx_clean(struct aq_ring_s *self)
 			}
 		}
 
-		if (unlikely(buff->is_eop))
-			dev_kfree_skb_any(buff->skb);
+		if (unlikely(buff->is_eop)) {
+			++self->stats.rx.packets;
+			self->stats.tx.bytes += buff->skb->len;
 
+			dev_kfree_skb_any(buff->skb);
+		}
 		buff->pa = 0U;
 		buff->eop_index = 0xffffU;
 		self->sw_head = aq_ring_next_dx(self, self->sw_head);
-- 
2.17.1