Re: FAILED: patch "[PATCH] can: raw: add missing refcount for memory leak fix" failed to apply to 5.15-stable tree

Oliver Hartkopp
2023-08-27T11:15:47Z

Hello Greg,

the dev_tracker including netdev_put() and netdev_hold() has been
introduced in Linux 6.0.

I send out a stable backport patch to this group of people for 5.15 :

"[PATCH stable < v6.0] can: raw: add missing refcount for memory leak fix"

Best regards,
Oliver

On 27.08.23 12:32, gregkh@linuxfoundation.org wrote:
>
> The patch below does not apply to the 5.15-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.
>
> To reproduce the conflict and resubmit, you may use the following commands:
>
> git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
> git checkout FETCH_HEAD
> git cherry-pick -x c275a176e4b69868576e543409927ae75e3a3288
> # <resolve conflicts, build, test, etc.>
> git commit -s
> git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2023082737-cavity-bloating-1779@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..
>
> Possible dependencies:
>
> c275a176e4b6 ("can: raw: add missing refcount for memory leak fix")
> ee8b94c8510c ("can: raw: fix receiver memory leak")
>
> thanks,
>
> greg k-h
>
> ------------------ original commit in Linus's tree ------------------
>
> From c275a176e4b69868576e543409927ae75e3a3288 Mon Sep 17 00:00:00 2001
> From: Oliver Hartkopp <socketcan@hartkopp.net>
> Date: Mon, 21 Aug 2023 16:45:47 +0200
> Subject: [PATCH] can: raw: add missing refcount for memory leak fix
>
> Commit ee8b94c8510c ("can: raw: fix receiver memory leak") introduced
> a new reference to the CAN netdevice that has assigned CAN filters.
> But this new ro->dev reference did not maintain its own refcount which
> lead to another KASAN use-after-free splat found by Eric Dumazet.
>
> This patch ensures a proper refcount for the CAN nedevice.
>
> Fixes: ee8b94c8510c ("can: raw: fix receiver memory leak")
> Reported-by: Eric Dumazet <edumazet@google.com>
> Cc: Ziyang Xuan <william.xuanziyang@huawei.com>
> Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
> Link: https://lore.kernel.org/r/20230821144547.6658-3-socketcan@hartkopp.net
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
>
> diff --git a/net/can/raw.c b/net/can/raw.c
> index e10f59375659..d50c3f3d892f 100644
> --- a/net/can/raw.c
> +++ b/net/can/raw.c
> @@ -85,6 +85,7 @@ struct raw_sock {
> int bound;
> int ifindex;
> struct net_device *dev;
> + netdevice_tracker dev_tracker;
> struct list_head notifier;
> int loopback;
> int recv_own_msgs;
> @@ -285,8 +286,10 @@ static void raw_notify(struct raw_sock *ro, unsigned long msg,
> case NETDEV_UNREGISTER:
> lock_sock(sk);
> /* remove current filters & unregister */
> - if (ro->bound)
> + if (ro->bound) {
> raw_disable_allfilters(dev_net(dev), dev, sk);
> + netdev_put(dev, &ro->dev_tracker);
> + }
>
> if (ro->count > 1)
> kfree(ro->filter);
> @@ -391,10 +394,12 @@ static int raw_release(struct socket *sock)
>
> /* remove current filters & unregister */
> if (ro->bound) {
> - if (ro->dev)
> + if (ro->dev) {
> raw_disable_allfilters(dev_net(ro->dev), ro->dev, sk);
> - else
> + netdev_put(ro->dev, &ro->dev_tracker);
> + } else {
> raw_disable_allfilters(sock_net(sk), NULL, sk);
> + }
> }
>
> if (ro->count > 1)
> @@ -445,10 +450,10 @@ static int raw_bind(struct socket *sock, struct sockaddr *uaddr, int len)
> goto out;
> }
> if (dev->type != ARPHRD_CAN) {
> - dev_put(dev);
> err = -ENODEV;
> - goto out;
> + goto out_put_dev;
> }
> +
> if (!(dev->flags & IFF_UP))
> notify_enetdown = 1;
>
> @@ -456,7 +461,9 @@ static int raw_bind(struct socket *sock, struct sockaddr *uaddr, int len)
>
> /* filters set by default/setsockopt */
> err = raw_enable_allfilters(sock_net(sk), dev, sk);
> - dev_put(dev);
> + if (err)
> + goto out_put_dev;
> +
> } else {
> ifindex = 0;
>
> @@ -467,18 +474,28 @@ static int raw_bind(struct socket *sock, struct sockaddr *uaddr, int len)
> if (!err) {
> if (ro->bound) {
> /* unregister old filters */
> - if (ro->dev)
> + if (ro->dev) {
> raw_disable_allfilters(dev_net(ro->dev),
> ro->dev, sk);
> - else
> + /* drop reference to old ro->dev */
> + netdev_put(ro->dev, &ro->dev_tracker);
> + } else {
> raw_disable_allfilters(sock_net(sk), NULL, sk);
> + }
> }
> ro->ifindex = ifindex;
> ro->bound = 1;
> + /* bind() ok -> hold a reference for new ro->dev */
> ro->dev = dev;
> + if (ro->dev)
> + netdev_hold(ro->dev, &ro->dev_tracker, GFP_KERNEL);
> }
>
> - out:
> +out_put_dev:
> + /* remove potential reference from dev_get_by_index() */
> + if (dev)
> + dev_put(dev);
> +out:
> release_sock(sk);
> rtnl_unlock();
>
>