From f2ce04f29e86f5b267a5266a73dbc278a8f7b055 Mon Sep 17 00:00:00 2001 From: Luiz Augusto von Dentz Date: Thu, 15 Oct 2020 11:32:41 +0200 Subject: [PATCH] Bluetooth: L2CAP: Fix calling sk_filter on non-socket based channel Only sockets will have the chan->data set to an actual sk, channels like A2MP would have its own data which would likely cause a crash when calling sk_filter, in order to fix this a new callback has been introduced so channels can implement their own filtering if necessary. Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Marcel Holtmann CVE-2020-12351 (cherry picked from commit f19425641cb2572a33cb074d5e30283720bd4d22 linux-next) Signed-off-by: Stefan Bader Acked-by: Andrea Righi Acked-by: Colin Ian King Signed-off-by: Andrea Righi --- include/net/bluetooth/l2cap.h | 2 ++ net/bluetooth/l2cap_core.c | 7 ++++--- net/bluetooth/l2cap_sock.c | 14 ++++++++++++++ 3 files changed, 20 insertions(+), 3 deletions(-) diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h index 8f1e6a7a2df84..1d1232917de72 100644 --- a/include/net/bluetooth/l2cap.h +++ b/include/net/bluetooth/l2cap.h @@ -665,6 +665,8 @@ struct l2cap_ops { struct sk_buff *(*alloc_skb) (struct l2cap_chan *chan, unsigned long hdr_len, unsigned long len, int nb); + int (*filter) (struct l2cap_chan * chan, + struct sk_buff *skb); }; struct l2cap_conn { diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c index fe913a5c754a8..129cbef8e5605 100644 --- a/net/bluetooth/l2cap_core.c +++ b/net/bluetooth/l2cap_core.c @@ -7302,9 +7302,10 @@ static int l2cap_data_rcv(struct l2cap_chan *chan, struct sk_buff *skb) goto drop; } - if ((chan->mode == L2CAP_MODE_ERTM || - chan->mode == L2CAP_MODE_STREAMING) && sk_filter(chan->data, skb)) - goto drop; + if (chan->ops->filter) { + if (chan->ops->filter(chan, skb)) + goto drop; + } if (!control->sframe) { int err; diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c index a995d2c51fa7f..c7fc28a465fdb 100644 --- a/net/bluetooth/l2cap_sock.c +++ b/net/bluetooth/l2cap_sock.c @@ -1663,6 +1663,19 @@ static void l2cap_sock_suspend_cb(struct l2cap_chan *chan) sk->sk_state_change(sk); } +static int l2cap_sock_filter(struct l2cap_chan *chan, struct sk_buff *skb) +{ + struct sock *sk = chan->data; + + switch (chan->mode) { + case L2CAP_MODE_ERTM: + case L2CAP_MODE_STREAMING: + return sk_filter(sk, skb); + } + + return 0; +} + static const struct l2cap_ops l2cap_chan_ops = { .name = "L2CAP Socket Interface", .new_connection = l2cap_sock_new_connection_cb, @@ -1678,6 +1691,7 @@ static const struct l2cap_ops l2cap_chan_ops = { .get_sndtimeo = l2cap_sock_get_sndtimeo_cb, .get_peer_pid = l2cap_sock_get_peer_pid_cb, .alloc_skb = l2cap_sock_alloc_skb_cb, + .filter = l2cap_sock_filter, }; static void l2cap_sock_destruct(struct sock *sk)