[v3] do not leave dangling sk pointers in pf->create functions

[PATCH net-next v3 3/9] Bluetooth: RFCOMM: avoid leaving dangling sk pointer in rfcomm_sock_alloc()

Posted by Ignat Korchagin 1 month, 1 week ago

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@cloudflare.com>
---
 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 f48250e3f2e1..355e1a1698f5 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

Re: [PATCH net-next v3 3/9] Bluetooth: RFCOMM: avoid leaving dangling sk pointer in rfcomm_sock_alloc()

Posted by Kuniyuki Iwashima 1 month, 1 week ago

From: Ignat Korchagin <ignat@cloudflare.com>
Date: Mon, 14 Oct 2024 16:38:02 +0100
> 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@cloudflare.com>

Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>

Re: [PATCH net-next v3 3/9] Bluetooth: RFCOMM: avoid leaving dangling sk pointer in rfcomm_sock_alloc()

Posted by Eric Dumazet 1 month, 1 week ago

On Mon, Oct 14, 2024 at 11:30 PM Kuniyuki Iwashima <kuniyu@amazon.com> wrote:
>
> From: Ignat Korchagin <ignat@cloudflare.com>
> Date: Mon, 14 Oct 2024 16:38:02 +0100
> > 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@cloudflare.com>
>
> Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>

Reviewed-by: Eric Dumazet <edumazet@google.com>