[PATCH] Bluetooth: hci_conn: fix potential double free in le_scan_cleanup()

[PATCH] Bluetooth: hci_conn: fix potential double free in le_scan_cleanup()

[Jianglei Nie]

When "c == conn" is true, hci_conn_cleanup() is called. The
hci_conn_cleanup() calls hci_dev_put() and hci_conn_put() in
its function implementation. hci_dev_put() and hci_conn_put()
will free the relevant resource if the reference count reaches
zero, which may lead to a double free when hci_dev_put() and
hci_conn_put() are called again.

We should add a return to this function after hci_conn_cleanup()
is called.

Signed-off-by: Jianglei Nie <niejianglei2021@163.com>
---
 net/bluetooth/hci_conn.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index fe803bee419a..7b3e91eb9fa3 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -166,6 +166,7 @@ static void le_scan_cleanup(struct work_struct *work)
 	if (c == conn) {
 		hci_connect_le_scan_cleanup(conn);
 		hci_conn_cleanup(conn);
+		return;
 	}
 
 	hci_dev_unlock(hdev);
-- 
2.25.1

Re: [PATCH] Bluetooth: hci_conn: fix potential double free in le_scan_cleanup()

[Paolo Abeni]

On Thu, 2022-05-26 at 17:49 +0800, Jianglei Nie wrote:
> When "c == conn" is true, hci_conn_cleanup() is called. The
> hci_conn_cleanup() calls hci_dev_put() and hci_conn_put() in
> its function implementation. hci_dev_put() and hci_conn_put()
> will free the relevant resource if the reference count reaches
> zero, which may lead to a double free when hci_dev_put() and
> hci_conn_put() are called again.
> 
> We should add a return to this function after hci_conn_cleanup()
> is called.
> 
> Signed-off-by: Jianglei Nie <niejianglei2021@163.com>
> ---
>  net/bluetooth/hci_conn.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
> index fe803bee419a..7b3e91eb9fa3 100644
> --- a/net/bluetooth/hci_conn.c
> +++ b/net/bluetooth/hci_conn.c
> @@ -166,6 +166,7 @@ static void le_scan_cleanup(struct work_struct *work)
>  	if (c == conn) {
>  		hci_connect_le_scan_cleanup(conn);
>  		hci_conn_cleanup(conn);
> +		return;

This looks not correct. At very least you should release the
hci_dev_lock.

Cheers,

Paolo

Re: [PATCH] Bluetooth: hci_conn: fix potential double free in le_scan_cleanup()

[Luiz Augusto von Dentz]

Hi,

On Thu, May 26, 2022 at 4:24 AM Paolo Abeni <pabeni@redhat.com> wrote:
>
> On Thu, 2022-05-26 at 17:49 +0800, Jianglei Nie wrote:
> > When "c == conn" is true, hci_conn_cleanup() is called. The
> > hci_conn_cleanup() calls hci_dev_put() and hci_conn_put() in
> > its function implementation. hci_dev_put() and hci_conn_put()
> > will free the relevant resource if the reference count reaches
> > zero, which may lead to a double free when hci_dev_put() and
> > hci_conn_put() are called again.
> >
> > We should add a return to this function after hci_conn_cleanup()
> > is called.
> >
> > Signed-off-by: Jianglei Nie <niejianglei2021@163.com>
> > ---
> >  net/bluetooth/hci_conn.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
> > index fe803bee419a..7b3e91eb9fa3 100644
> > --- a/net/bluetooth/hci_conn.c
> > +++ b/net/bluetooth/hci_conn.c
> > @@ -166,6 +166,7 @@ static void le_scan_cleanup(struct work_struct *work)
> >       if (c == conn) {
> >               hci_connect_le_scan_cleanup(conn);
> >               hci_conn_cleanup(conn);
> > +             return;
>
> This looks not correct. At very least you should release the
> hci_dev_lock.

Yep, it should probably use break instead of return.

> Cheers,
>
> Paolo
>


-- 
Luiz Augusto von Dentz