[PATCH v2 1/2] Bluetooth: SCO: Fix UAF on sco_sock_timeout

[PATCH v2 1/2] Bluetooth: SCO: Fix UAF on sco_sock_timeout

[Luiz Augusto von Dentz]

From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

conn->sk maybe have been unlinked/freed while waiting for sco_conn_lock
so this checks if the conn->sk is still valid by checking if it part of
sco_sk_list.

Reported-by: syzbot+4c0d0c4cde787116d465@syzkaller.appspotmail.com
Tested-by: syzbot+4c0d0c4cde787116d465@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=4c0d0c4cde787116d465
Fixes: ba316be1b6a0 ("Bluetooth: schedule SCO timeouts with delayed_work")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
---
 include/net/bluetooth/bluetooth.h |  1 +
 net/bluetooth/af_bluetooth.c      | 22 ++++++++++++++++++++++
 net/bluetooth/sco.c               | 18 ++++++++++++------
 3 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/include/net/bluetooth/bluetooth.h b/include/net/bluetooth/bluetooth.h
index 5d655e109b2c..f66bc85c6411 100644
--- a/include/net/bluetooth/bluetooth.h
+++ b/include/net/bluetooth/bluetooth.h
@@ -403,6 +403,7 @@ int  bt_sock_register(int proto, const struct net_proto_family *ops);
 void bt_sock_unregister(int proto);
 void bt_sock_link(struct bt_sock_list *l, struct sock *s);
 void bt_sock_unlink(struct bt_sock_list *l, struct sock *s);
+bool bt_sock_linked(struct bt_sock_list *l, struct sock *s);
 struct sock *bt_sock_alloc(struct net *net, struct socket *sock,
 			   struct proto *prot, int proto, gfp_t prio, int kern);
 int  bt_sock_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
diff --git a/net/bluetooth/af_bluetooth.c b/net/bluetooth/af_bluetooth.c
index e39fba5565c5..0b4d0a8bd361 100644
--- a/net/bluetooth/af_bluetooth.c
+++ b/net/bluetooth/af_bluetooth.c
@@ -185,6 +185,28 @@ void bt_sock_unlink(struct bt_sock_list *l, struct sock *sk)
 }
 EXPORT_SYMBOL(bt_sock_unlink);
 
+bool bt_sock_linked(struct bt_sock_list *l, struct sock *s)
+{
+	struct sock *sk;
+
+	if (!l || !s)
+		return false;
+
+	read_lock(&l->lock);
+
+	sk_for_each(sk, &l->head) {
+		if (s == sk) {
+			read_unlock(&l->lock);
+			return true;
+		}
+	}
+
+	read_unlock(&l->lock);
+
+	return false;
+}
+EXPORT_SYMBOL(bt_sock_linked);
+
 void bt_accept_enqueue(struct sock *parent, struct sock *sk, bool bh)
 {
 	const struct cred *old_cred;
diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c
index a5ac160c592e..1c7252a36866 100644
--- a/net/bluetooth/sco.c
+++ b/net/bluetooth/sco.c
@@ -76,6 +76,16 @@ struct sco_pinfo {
 #define SCO_CONN_TIMEOUT	(HZ * 40)
 #define SCO_DISCONN_TIMEOUT	(HZ * 2)
 
+static struct sock *sco_sock_hold(struct sco_conn *conn)
+{
+	if (!conn || !bt_sock_linked(&sco_sk_list, conn->sk))
+		return NULL;
+
+	sock_hold(conn->sk);
+
+	return conn->sk;
+}
+
 static void sco_sock_timeout(struct work_struct *work)
 {
 	struct sco_conn *conn = container_of(work, struct sco_conn,
@@ -87,9 +97,7 @@ static void sco_sock_timeout(struct work_struct *work)
 		sco_conn_unlock(conn);
 		return;
 	}
-	sk = conn->sk;
-	if (sk)
-		sock_hold(sk);
+	sk = sco_sock_hold(conn);
 	sco_conn_unlock(conn);
 
 	if (!sk)
@@ -194,9 +202,7 @@ static void sco_conn_del(struct hci_conn *hcon, int err)
 
 	/* Kill socket */
 	sco_conn_lock(conn);
-	sk = conn->sk;
-	if (sk)
-		sock_hold(sk);
+	sk = sco_sock_hold(conn);
 	sco_conn_unlock(conn);
 
 	if (sk) {
-- 
2.47.0

[PATCH v2 2/2] Bluetooth: ISO: Fix UAF on iso_sock_timeout

[Luiz Augusto von Dentz]

From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

conn->sk maybe have been unlinked/freed while waiting for iso_conn_lock
so this checks if the conn->sk is still valid by checking if it part of
iso_sk_list.

Fixes: ccf74f2390d6 ("Bluetooth: Add BTPROTO_ISO socket type")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
---
 net/bluetooth/iso.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/net/bluetooth/iso.c b/net/bluetooth/iso.c
index c9eefb43bf47..7a83e400ac77 100644
--- a/net/bluetooth/iso.c
+++ b/net/bluetooth/iso.c
@@ -93,6 +93,16 @@ static struct sock *iso_get_sock(bdaddr_t *src, bdaddr_t *dst,
 #define ISO_CONN_TIMEOUT	(HZ * 40)
 #define ISO_DISCONN_TIMEOUT	(HZ * 2)
 
+static struct sock *iso_sock_hold(struct iso_conn *conn)
+{
+	if (!conn || !bt_sock_linked(&iso_sk_list, conn->sk))
+		return NULL;
+
+	sock_hold(conn->sk);
+
+	return conn->sk;
+}
+
 static void iso_sock_timeout(struct work_struct *work)
 {
 	struct iso_conn *conn = container_of(work, struct iso_conn,
@@ -100,9 +110,7 @@ static void iso_sock_timeout(struct work_struct *work)
 	struct sock *sk;
 
 	iso_conn_lock(conn);
-	sk = conn->sk;
-	if (sk)
-		sock_hold(sk);
+	sk = iso_sock_hold(conn);
 	iso_conn_unlock(conn);
 
 	if (!sk)
@@ -209,9 +217,7 @@ static void iso_conn_del(struct hci_conn *hcon, int err)
 
 	/* Kill socket */
 	iso_conn_lock(conn);
-	sk = conn->sk;
-	if (sk)
-		sock_hold(sk);
+	sk = iso_sock_hold(conn);
 	iso_conn_unlock(conn);
 
 	if (sk) {
-- 
2.47.0

Re: [PATCH v2 1/2] Bluetooth: SCO: Fix UAF on sco_sock_timeout

[patchwork-bot+bluetooth]

Hello:

This series was applied to bluetooth/bluetooth-next.git (master)
by Luiz Augusto von Dentz <luiz.von.dentz@intel.com>:

On Tue, 22 Oct 2024 16:34:20 -0400 you wrote:
> From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
> 
> conn->sk maybe have been unlinked/freed while waiting for sco_conn_lock
> so this checks if the conn->sk is still valid by checking if it part of
> sco_sk_list.
> 
> Reported-by: syzbot+4c0d0c4cde787116d465@syzkaller.appspotmail.com
> Tested-by: syzbot+4c0d0c4cde787116d465@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=4c0d0c4cde787116d465
> Fixes: ba316be1b6a0 ("Bluetooth: schedule SCO timeouts with delayed_work")
> Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
> 
> [...]

Here is the summary with links:
  - [v2,1/2] Bluetooth: SCO: Fix UAF on sco_sock_timeout
    https://git.kernel.org/bluetooth/bluetooth-next/c/300b75192c4d
  - [v2,2/2] Bluetooth: ISO: Fix UAF on iso_sock_timeout
    https://git.kernel.org/bluetooth/bluetooth-next/c/fb4560832d4c

You are awesome, thank you!
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