[PATCH AUTOSEL 4.9 1/7] net: ieee802154: at86rf230: Stop leaking skb's

From: Miquel Raynal <miquel.raynal@bootlin.com>

[ Upstream commit e5ce576d45bf72fd0e3dc37eff897bfcc488f6a9 ]

Upon error the ieee802154_xmit_complete() helper is not called. Only
ieee802154_wake_queue() is called manually. In the Tx case we then leak
the skb structure.

Free the skb structure upon error before returning when appropriate.

As the 'is_tx = 0' cannot be moved in the complete handler because of a
possible race between the delay in switching to STATE_RX_AACK_ON and a
new interrupt, we introduce an intermediate 'was_tx' boolean just for
this purpose.

There is no Fixes tag applying here, many changes have been made on this
area and the issue kind of always existed.

Suggested-by: Alexander Aring <alex.aring@gmail.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Acked-by: Alexander Aring <aahringo@redhat.com>
Link: https://lore.kernel.org/r/20220125121426.848337-4-miquel.raynal@bootlin.com
Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/ieee802154/at86rf230.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ieee802154/at86rf230.c b/drivers/net/ieee802154/at86rf230.c
index ce3b7fb7eda09..80c8e9abb402e 100644
--- a/drivers/net/ieee802154/at86rf230.c
+++ b/drivers/net/ieee802154/at86rf230.c

@@ -108,6 +108,7 @@ struct at86rf230_local {
 	unsigned long cal_timeout;
 	bool is_tx;
 	bool is_tx_from_off;
+	bool was_tx;
 	u8 tx_retry;
 	struct sk_buff *tx_skb;
 	struct at86rf230_state_change tx;

@@ -351,7 +352,11 @@ at86rf230_async_error_recover_complete(void *context)
 	if (ctx->free)
 		kfree(ctx);
 
-	ieee802154_wake_queue(lp->hw);
+	if (lp->was_tx) {
+		lp->was_tx = 0;
+		dev_kfree_skb_any(lp->tx_skb);
+		ieee802154_wake_queue(lp->hw);
+	}
 }
 
 static void

@@ -360,7 +365,11 @@ at86rf230_async_error_recover(void *context)
 	struct at86rf230_state_change *ctx = context;
 	struct at86rf230_local *lp = ctx->lp;
 
-	lp->is_tx = 0;
+	if (lp->is_tx) {
+		lp->was_tx = 1;
+		lp->is_tx = 0;
+	}
+
 	at86rf230_async_state_change(lp, ctx, STATE_RX_AACK_ON,
 				     at86rf230_async_error_recover_complete);
 }

-- 
2.34.1

From: Duoming Zhou <redacted>

[ Upstream commit 4e0f718daf97d47cf7dec122da1be970f145c809 ]

The previous commit 1ade48d0c27d ("ax25: NPD bug when detaching
AX25 device") introduce lock_sock() into ax25_kill_by_device to
prevent NPD bug. But the concurrency NPD or UAF bug will occur,
when lock_sock() or release_sock() dereferences the ax25_cb->sock.

The NULL pointer dereference bug can be shown as below:

ax25_kill_by_device()        | ax25_release()
                             |   ax25_destroy_socket()
                             |     ax25_cb_del()
  ...                        |     ...
                             |     ax25->sk=NULL;
  lock_sock(s->sk); //(1)    |
  s->ax25_dev = NULL;        |     ...
  release_sock(s->sk); //(2) |
  ...                        |

The root cause is that the sock is set to null before dereference
site (1) or (2). Therefore, this patch extracts the ax25_cb->sock
in advance, and uses ax25_list_lock to protect it, which can synchronize
with ax25_cb_del() and ensure the value of sock is not null before
dereference sites.

The concurrency UAF bug can be shown as below:

ax25_kill_by_device()        | ax25_release()
                             |   ax25_destroy_socket()
  ...                        |   ...
                             |   sock_put(sk); //FREE
  lock_sock(s->sk); //(1)    |
  s->ax25_dev = NULL;        |   ...
  release_sock(s->sk); //(2) |
  ...                        |

The root cause is that the sock is released before dereference
site (1) or (2). Therefore, this patch uses sock_hold() to increase
the refcount of sock and uses ax25_list_lock to protect it, which
can synchronize with ax25_cb_del() in ax25_destroy_socket() and
ensure the sock wil not be released before dereference sites.

Signed-off-by: Duoming Zhou <redacted>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/ax25/af_ax25.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c
index f4c8567e91b38..c4ef1be59cb19 100644
--- a/net/ax25/af_ax25.c
+++ b/net/ax25/af_ax25.c

@@ -80,6 +80,7 @@ static void ax25_kill_by_device(struct net_device *dev)
 {
 	ax25_dev *ax25_dev;
 	ax25_cb *s;
+	struct sock *sk;
 
 	if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
 		return;

@@ -88,13 +89,15 @@ static void ax25_kill_by_device(struct net_device *dev)
 again:
 	ax25_for_each(s, &ax25_list) {
 		if (s->ax25_dev == ax25_dev) {
+			sk = s->sk;
+			sock_hold(sk);
 			spin_unlock_bh(&ax25_list_lock);
-			lock_sock(s->sk);
+			lock_sock(sk);
 			s->ax25_dev = NULL;
-			release_sock(s->sk);
+			release_sock(sk);
 			ax25_disconnect(s, ENETUNREACH);
 			spin_lock_bh(&ax25_list_lock);
-
+			sock_put(sk);
 			/* The entry could have been deleted from the
 			 * list meanwhile and thus the next pointer is
 			 * no longer valid.  Play it safe and restart

-- 
2.34.1