[PATCH v2 4/8] Bluetooth: RFCOMM: avoid leaving dangling sk pointer in rfcomm_sock_alloc()

From: Ignat Korchagin
Date: Mon Oct 07 2024 - 17:37:07 EST


bt_sock_alloc() attaches allocated sk object to the provided sock object.
If rfcomm_dlc_alloc() fails, we release the sk object, but leave the
dangling pointer in the sock object, which may cause use-after-free.

Fix this by swapping calls to bt_sock_alloc() and rfcomm_dlc_alloc().

Signed-off-by: Ignat Korchagin <ignat@xxxxxxxxxxxxxx>
---
net/bluetooth/rfcomm/sock.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/net/bluetooth/rfcomm/sock.c b/net/bluetooth/rfcomm/sock.c
index 37d63d768afb..0d0c4311da57 100644
--- a/net/bluetooth/rfcomm/sock.c
+++ b/net/bluetooth/rfcomm/sock.c
@@ -274,13 +274,13 @@ static struct sock *rfcomm_sock_alloc(struct net *net, struct socket *sock,
struct rfcomm_dlc *d;
struct sock *sk;

- sk = bt_sock_alloc(net, sock, &rfcomm_proto, proto, prio, kern);
- if (!sk)
+ d = rfcomm_dlc_alloc(prio);
+ if (!d)
return NULL;

- d = rfcomm_dlc_alloc(prio);
- if (!d) {
- sk_free(sk);
+ sk = bt_sock_alloc(net, sock, &rfcomm_proto, proto, prio, kern);
+ if (!sk) {
+ rfcomm_dlc_free(d);
return NULL;
}

--
2.39.5