[PATCH 5.5 129/176] net: atlantic: fix use after free kasan warn

Greg Kroah-Hartman
2020-03-03T17:49:54Z

From: Pavel Belous <pbelous@marvell.com>

commit a4980919ad6a7be548d499bc5338015e1a9191c6 upstream.

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@fastmail.fm>
Signed-off-by: Igor Russkikh <irusskikh@marvell.com>
Signed-off-by: Pavel Belous <pbelous@marvell.com>
Signed-off-by: Dmitry Bogdanov <dbogdanov@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
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(-)

--- 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, s
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;
}
--- 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 *
}
}

- 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);