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Sat, 27 Jun 2026 17:28:11 -0700 (PDT) Received: from Dev-Null-MSI ([2a0d:3344:52ac:a808:98a4:4381:be45:536f]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-492690100c7sm216713895e9.12.2026.06.27.17.28.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 27 Jun 2026 17:28:10 -0700 (PDT) From: Yousef Alhouseen To: Jakub Kicinski , Andrew Lunn Cc: davem@davemloft.net, Eric Dumazet , Paolo Abeni , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, syzbot+6c25f4750230faf70be9@syzkaller.appspotmail.com, Yousef Alhouseen Subject: [PATCH] netdevsim: remove ethtool debugfs files before freeing netdev Date: Sun, 28 Jun 2026 02:28:04 +0200 Message-ID: <20260628002804.24214-1-alhouseenyousef@gmail.com> X-Mailer: git-send-email 2.54.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The ethtool debugfs files point directly into struct netdevsim, which is allocated as net_device private data. Their containing port directory is removed only after nsim_destroy() calls free_netdev(). An open simple-attribute file can consequently dereference the freed private data before the directory is removed. KASAN observed this in debugfs_u32_get() during network namespace teardown. Track and remove the ethtool subtree before free_netdev() on both the normal and registration-failure paths. debugfs removal drains active file users before returning. Fixes: ff1f7c17fb20 ("netdevsim: add pause frame stats") Reported-by: syzbot+6c25f4750230faf70be9@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=6c25f4750230faf70be9 Cc: stable@vger.kernel.org Signed-off-by: Yousef Alhouseen --- drivers/net/netdevsim/ethtool.c | 6 ++++++ drivers/net/netdevsim/netdev.c | 2 ++ drivers/net/netdevsim/netdevsim.h | 2 ++ 3 files changed, 10 insertions(+) diff --git a/drivers/net/netdevsim/ethtool.c b/drivers/net/netdevsim/ethtool.c index 9350ba48eb81..025ea79879f3 100644 --- a/drivers/net/netdevsim/ethtool.c +++ b/drivers/net/netdevsim/ethtool.c @@ -252,6 +252,7 @@ void nsim_ethtool_init(struct netdevsim *ns) ns->ethtool.channels = ns->nsim_bus_dev->num_queues; ethtool = debugfs_create_dir("ethtool", ns->nsim_dev_port->ddir); + ns->ethtool_ddir = ethtool; debugfs_create_u32("get_err", 0600, ethtool, &ns->ethtool.get_err); debugfs_create_u32("set_err", 0600, ethtool, &ns->ethtool.set_err); @@ -272,3 +273,8 @@ void nsim_ethtool_init(struct netdevsim *ns) debugfs_create_u32("tx_max_pending", 0600, dir, &ns->ethtool.ring.tx_max_pending); } + +void nsim_ethtool_fini(struct netdevsim *ns) +{ + debugfs_remove(ns->ethtool_ddir); +} diff --git a/drivers/net/netdevsim/netdev.c b/drivers/net/netdevsim/netdev.c index 27e5f109f933..4e9d7e10b527 100644 --- a/drivers/net/netdevsim/netdev.c +++ b/drivers/net/netdevsim/netdev.c @@ -1165,6 +1165,7 @@ struct netdevsim *nsim_create(struct nsim_dev *nsim_dev, return ns; err_free_netdev: + nsim_ethtool_fini(ns); free_netdev(dev); return ERR_PTR(err); } @@ -1178,6 +1179,7 @@ void nsim_destroy(struct netdevsim *ns) debugfs_remove(ns->vlan_dfs); debugfs_remove(ns->qr_dfs); debugfs_remove(ns->pp_dfs); + nsim_ethtool_fini(ns); if (ns->nb.notifier_call) unregister_netdevice_notifier_dev_net(ns->netdev, &ns->nb, diff --git a/drivers/net/netdevsim/netdevsim.h b/drivers/net/netdevsim/netdevsim.h index 4c9cc96dcec3..64f77f93d937 100644 --- a/drivers/net/netdevsim/netdevsim.h +++ b/drivers/net/netdevsim/netdevsim.h @@ -154,6 +154,7 @@ struct netdevsim { struct dentry *pp_dfs; struct dentry *qr_dfs; struct dentry *vlan_dfs; + struct dentry *ethtool_ddir; struct nsim_ethtool ethtool; struct netdevsim __rcu *peer; @@ -169,6 +170,7 @@ void nsim_destroy(struct netdevsim *ns); bool netdev_is_nsim(struct net_device *dev); void nsim_ethtool_init(struct netdevsim *ns); +void nsim_ethtool_fini(struct netdevsim *ns); void nsim_udp_tunnels_debugfs_create(struct nsim_dev *nsim_dev); int nsim_udp_tunnels_info_create(struct nsim_dev *nsim_dev, -- 2.54.0