From: Doruk Tan Ozturk <doruk@0sec.ai> stable inclusion from stable-v6.12.104 commit d07133fe1befae9a1e4c4c5e46ef0b73d2992020 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/18212 CVE: CVE-2026-74677 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit fde39b8a521780391fb4e5bda2c0aa4928947f12 upstream. ipheth_sndbulk_callback() re-arms the carrier-check work on any non-zero URB status: else schedule_delayed_work(&dev->carrier_work, 0); Nothing ties that to the interface being up, so the work can be armed again after ipheth_close() has already drained it, and stay armed until the netdev whose private area embeds it is freed. On unplug with a TX URB in flight, ipheth_disconnect() drains the work through unregister_netdev() -> ipheth_close() -> cancel_delayed_work_sync() and only then calls ipheth_kill_urbs(). usb_kill_urb() completes the in-flight TX URB with -ENOENT, so ipheth_sndbulk_callback() runs after the drain and re-arms carrier_work. The same completion also re-arms the work if the interface is only brought down while a TX URB is in flight, and ipheth_carrier_check_work() then keeps re-queueing itself once a second. unregister_netdev() does not call ipheth_close() for an already-down interface, so nothing drains it on the later unplug either. In both cases free_netdev() frees the netdev while carrier_work is still pending, and ipheth_carrier_check_work() dereferences freed memory. Tie the work to the interface state instead of chasing the completion: disable it in ipheth_close() and enable it in ipheth_open(), so a schedule_delayed_work() from the URB completion is a no-op whenever the interface is not up. disable_delayed_work_sync() also waits for a running instance, so it fully replaces the cancel_delayed_work_sync() it takes the place of. The work starts out disabled in ipheth_probe() so the enable/disable counts balance from the first open. Reproduced under KASAN on linux-next (next-20260731) with dummy_hcd and raw-gadget standing in for the device, driving the second path above (the interface is already down, so unregister_netdev() does not call ipheth_close()): 15 of 15 unpatched boots report a slab-use-after-free in __run_timers(), freed by ipheth_disconnect() and re-armed from ipheth_sndbulk_callback() via queue_delayed_work_on(). The same trigger on a kernel differing only by this patch reports 0 of 15, and the carrier check still functions across open/close cycles. The reproducer needs an attached USB device that stops draining bulk OUT, plus a link down and unplug, driven as root. It is not a privilege boundary crossing and no exploit primitive was developed. Found by 0sec (https://0sec.ai). Fixes: bb1b40c7cb86 ("usbnet: ipheth: prevent TX queue timeouts when device not ready") Cc: stable@vger.kernel.org Signed-off-by: Doruk Tan Ozturk <doruk@0sec.ai> Link: https://patch.msgid.link/20260802120602.42595-1-doruk@0sec.ai Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Zhang Qilong <zhangqilong3@huawei.com> --- drivers/net/usb/ipheth.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/net/usb/ipheth.c b/drivers/net/usb/ipheth.c index a19789b57190..a86d0a4dbd28 100644 --- a/drivers/net/usb/ipheth.c +++ b/drivers/net/usb/ipheth.c @@ -488,20 +488,25 @@ static int ipheth_open(struct net_device *net) retval = ipheth_rx_submit(dev, GFP_KERNEL); if (retval) return retval; + enable_delayed_work(&dev->carrier_work); schedule_delayed_work(&dev->carrier_work, IPHETH_CARRIER_CHECK_TIMEOUT); return retval; } static int ipheth_close(struct net_device *net) { struct ipheth_device *dev = netdev_priv(net); netif_stop_queue(net); - cancel_delayed_work_sync(&dev->carrier_work); + /* A TX URB can still complete with an error after this point and + * try to re-arm the carrier work. Disable it instead of cancelling + * it, so that such a schedule_delayed_work() is a no-op. + */ + disable_delayed_work_sync(&dev->carrier_work); return 0; } static netdev_tx_t ipheth_tx(struct sk_buff *skb, struct net_device *net) { @@ -631,10 +636,14 @@ static int ipheth_probe(struct usb_interface *intf, dev->rx_buf_len = IPHETH_RX_BUF_SIZE_NCM; dev->rcvbulk_callback = ipheth_rcvbulk_callback_ncm; } INIT_DELAYED_WORK(&dev->carrier_work, ipheth_carrier_check_work); + /* Armed only between ipheth_open() and ipheth_close(). Start out + * disabled so the enable/disable counts balance from the first open. + */ + disable_delayed_work(&dev->carrier_work); retval = ipheth_alloc_urbs(dev); if (retval) { dev_err(&intf->dev, "error allocating urbs: %d\n", retval); goto err_alloc_urbs; -- 2.43.0