kernel/linux.git/drivers/net/usb/usbnet.c, branch v6.12.80

qmi_wwan: allow max_mtu above hard_mtu to control rx_urb_size

2026-03-25T10:08:37+00:00

commit 55f854dd5bdd8e19b936a00ef1f8d776ac32c7b0 upstream. Commit c7159e960f14 ("usbnet: limit max_mtu based on device's hard_mtu") capped net->max_mtu to the device's hard_mtu in usbnet_probe(). While this correctly prevents oversized packets on standard USB network devices, it breaks the qmi_wwan driver. qmi_wwan relies on userspace (e.g. ModemManager) setting a large MTU on the wwan0 interface to configure rx_urb_size via usbnet_change_mtu(). QMI modems negotiate USB transfer sizes of 16,383 or 32,767 bytes, and the USB receive buffers must be sized accordingly. With max_mtu capped to hard_mtu (~1500 bytes), userspace can no longer raise the MTU, the receive buffers remain small, and download speeds drop from >300 Mbps to ~0.8 Mbps. Introduce a FLAG_NOMAXMTU driver flag that allows individual usbnet drivers to opt out of the max_mtu cap. Set this flag in qmi_wwan's driver_info structures to restore the previous behavior for QMI devices, while keeping the safety fix in place for all other usbnet drivers. Fixes: c7159e960f14 ("usbnet: limit max_mtu based on device's hard_mtu") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/lkml/CAPh3n803k8JcBPV5qEzUB-oKzWkAs-D5CU7z=Vd_nLRCr5ZqQg@mail.gmail.com/ Reported-by: Koen Vandeputte Tested-by: Daniele Palmas Signed-off-by: Laurent Vivier Link: https://patch.msgid.link/20260304134338.1785002-1-lvivier@redhat.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

usbnet: limit max_mtu based on device's hard_mtu

2026-01-30T09:28:42+00:00

[ Upstream commit c7159e960f1472a5493ac99aff0086ab1d683594 ] The usbnet driver initializes net->max_mtu to ETH_MAX_MTU before calling the device's bind() callback. When the bind() callback sets dev->hard_mtu based the device's actual capability (from CDC Ethernet's wMaxSegmentSize descriptor), max_mtu is never updated to reflect this hardware limitation). This allows userspace (DHCP or IPv6 RA) to configure MTU larger than the device can handle, leading to silent packet drops when the backend sends packet exceeding the device's buffer size. Fix this by limiting net->max_mtu to the device's hard_mtu after the bind callback returns. See https://gitlab.com/qemu-project/qemu/-/issues/3268 and https://bugs.passt.top/attachment.cgi?bugid=189 Fixes: f77f0aee4da4 ("net: use core MTU range checking in USB NIC drivers") Signed-off-by: Laurent Vivier Link: https://bugs.passt.top/show_bug.cgi?id=189 Reviewed-by: Stefano Brivio Link: https://patch.msgid.link/20260119075518.2774373-1-lvivier@redhat.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

usbnet: Fix using smp_processor_id() in preemptible code warnings

2026-01-08T09:15:01+00:00

[ Upstream commit 327cd4b68b4398b6c24f10eb2b2533ffbfc10185 ] Syzbot reported the following warning: BUG: using smp_processor_id() in preemptible [00000000] code: dhcpcd/2879 caller is usbnet_skb_return+0x74/0x490 drivers/net/usb/usbnet.c:331 CPU: 1 UID: 0 PID: 2879 Comm: dhcpcd Not tainted 6.15.0-rc4-syzkaller-00098-g615dca38c2ea #0 PREEMPT(voluntary) Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x16c/0x1f0 lib/dump_stack.c:120 check_preemption_disabled+0xd0/0xe0 lib/smp_processor_id.c:49 usbnet_skb_return+0x74/0x490 drivers/net/usb/usbnet.c:331 usbnet_resume_rx+0x4b/0x170 drivers/net/usb/usbnet.c:708 usbnet_change_mtu+0x1be/0x220 drivers/net/usb/usbnet.c:417 __dev_set_mtu net/core/dev.c:9443 [inline] netif_set_mtu_ext+0x369/0x5c0 net/core/dev.c:9496 netif_set_mtu+0xb0/0x160 net/core/dev.c:9520 dev_set_mtu+0xae/0x170 net/core/dev_api.c:247 dev_ifsioc+0xa31/0x18d0 net/core/dev_ioctl.c:572 dev_ioctl+0x223/0x10e0 net/core/dev_ioctl.c:821 sock_do_ioctl+0x19d/0x280 net/socket.c:1204 sock_ioctl+0x42f/0x6a0 net/socket.c:1311 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl fs/ioctl.c:892 [inline] __x64_sys_ioctl+0x190/0x200 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f For historical and portability reasons, the netif_rx() is usually run in the softirq or interrupt context, this commit therefore add local_bh_disable/enable() protection in the usbnet_resume_rx(). Fixes: 43daa96b166c ("usbnet: Stop RX Q on MTU change") Link: https://syzkaller.appspot.com/bug?id=81f55dfa587ee544baaaa5a359a060512228c1e1 Suggested-by: Jakub Kicinski Signed-off-by: Zqiang Link: https://patch.msgid.link/20251011070518.7095-1-qiang.zhang@linux.dev Signed-off-by: Paolo Abeni [Harshit: Resolved conflicts due to missing commit: 2c04d279e857 ("net: usb: Convert tasklet API to new bottom half workqueue mechanism") in 6.12.y] Signed-off-by: Harshit Mogalapalli Signed-off-by: Greg Kroah-Hartman

usbnet: Prevents free active kevent

2025-11-13T20:33:58+00:00

[ Upstream commit 420c84c330d1688b8c764479e5738bbdbf0a33de ] The root cause of this issue are: 1. When probing the usbnet device, executing usbnet_link_change(dev, 0, 0); put the kevent work in global workqueue. However, the kevent has not yet been scheduled when the usbnet device is unregistered. Therefore, executing free_netdev() results in the "free active object (kevent)" error reported here. 2. Another factor is that when calling usbnet_disconnect()->unregister_netdev(), if the usbnet device is up, ndo_stop() is executed to cancel the kevent. However, because the device is not up, ndo_stop() is not executed. The solution to this problem is to cancel the kevent before executing free_netdev(). Fixes: a69e617e533e ("usbnet: Fix linkwatch use-after-free on disconnect") Reported-by: Sam Sun Closes: https://syzkaller.appspot.com/bug?extid=8bfd7bcc98f7300afb84 Signed-off-by: Lizhi Xu Link: https://patch.msgid.link/20251022024007.1831898-1-lizhi.xu@windriver.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net: usbnet: Fix the wrong netif_carrier_on() call

2025-08-15T10:14:12+00:00

commit 8466d393700f9ccef68134d3349f4e0a087679b9 upstream. The commit referenced in the Fixes tag causes usbnet to malfunction (identified via git bisect). Post-commit, my external RJ45 LAN cable fails to connect. Linus also reported the same issue after pulling that commit. The code has a logic error: netif_carrier_on() is only called when the link is already on. Fix this by moving the netif_carrier_on() call outside the if-statement entirely. This ensures it is always called when EVENT_LINK_CARRIER_ON is set and properly clears it regardless of the link state. Cc: stable@vger.kernel.org Cc: Armando Budianto Reviewed-by: Simon Horman Suggested-by: Linus Torvalds Link: https://lore.kernel.org/all/CAHk-=wjqL4uF0MG_c8+xHX1Vv8==sPYQrtzbdA3kzi96284nuQ@mail.gmail.com Closes: https://lore.kernel.org/netdev/CAHk-=wjKh8X4PT_mU1kD4GQrbjivMfPn-_hXa6han_BTDcXddw@mail.gmail.com Closes: https://lore.kernel.org/netdev/0752dee6-43d6-4e1f-81d2-4248142cccd2@gnuweeb.org Fixes: 0d9cfc9b8cb1 ("net: usbnet: Avoid potential RCU stall on LINK_CHANGE event") Signed-off-by: Ammar Faizi Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

net: usbnet: Avoid potential RCU stall on LINK_CHANGE event

2025-08-15T10:14:12+00:00

commit 0d9cfc9b8cb17dbc29a98792d36ec39a1cf1395f upstream. The Gemalto Cinterion PLS83-W modem (cdc_ether) is emitting confusing link up and down events when the WWAN interface is activated on the modem-side. Interrupt URBs will in consecutive polls grab: * Link Connected * Link Disconnected * Link Connected Where the last Connected is then a stable link state. When the system is under load this may cause the unlink_urbs() work in __handle_link_change() to not complete before the next usbnet_link_change() call turns the carrier on again, allowing rx_submit() to queue new SKBs. In that event the URB queue is filled faster than it can drain, ending up in a RCU stall: rcu: INFO: rcu_sched detected expedited stalls on CPUs/tasks: { 0-.... } 33108 jiffies s: 201 root: 0x1/. rcu: blocking rcu_node structures (internal RCU debug): Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 Call trace: arch_local_irq_enable+0x4/0x8 local_bh_enable+0x18/0x20 __netdev_alloc_skb+0x18c/0x1cc rx_submit+0x68/0x1f8 [usbnet] rx_alloc_submit+0x4c/0x74 [usbnet] usbnet_bh+0x1d8/0x218 [usbnet] usbnet_bh_tasklet+0x10/0x18 [usbnet] tasklet_action_common+0xa8/0x110 tasklet_action+0x2c/0x34 handle_softirqs+0x2cc/0x3a0 __do_softirq+0x10/0x18 ____do_softirq+0xc/0x14 call_on_irq_stack+0x24/0x34 do_softirq_own_stack+0x18/0x20 __irq_exit_rcu+0xa8/0xb8 irq_exit_rcu+0xc/0x30 el1_interrupt+0x34/0x48 el1h_64_irq_handler+0x14/0x1c el1h_64_irq+0x68/0x6c _raw_spin_unlock_irqrestore+0x38/0x48 xhci_urb_dequeue+0x1ac/0x45c [xhci_hcd] unlink1+0xd4/0xdc [usbcore] usb_hcd_unlink_urb+0x70/0xb0 [usbcore] usb_unlink_urb+0x24/0x44 [usbcore] unlink_urbs.constprop.0.isra.0+0x64/0xa8 [usbnet] __handle_link_change+0x34/0x70 [usbnet] usbnet_deferred_kevent+0x1c0/0x320 [usbnet] process_scheduled_works+0x2d0/0x48c worker_thread+0x150/0x1dc kthread+0xd8/0xe8 ret_from_fork+0x10/0x20 Get around the problem by delaying the carrier on to the scheduled work. This needs a new flag to keep track of the necessary action. The carrier ok check cannot be removed as it remains required for the LINK_RESET event flow. Fixes: 4b49f58fff00 ("usbnet: handle link change") Cc: stable@vger.kernel.org Signed-off-by: John Ernberg Link: https://patch.msgid.link/20250723102526.1305339-1-john.ernberg@actia.se Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

usbnet:fix NPE during rx_complete

2025-04-10T12:39:36+00:00

commit 51de3600093429e3b712e5f091d767babc5dd6df upstream. Missing usbnet_going_away Check in Critical Path. The usb_submit_urb function lacks a usbnet_going_away validation, whereas __usbnet_queue_skb includes this check. This inconsistency creates a race condition where: A URB request may succeed, but the corresponding SKB data fails to be queued. Subsequent processes: (e.g., rx_complete → defer_bh → __skb_unlink(skb, list)) attempt to access skb->next, triggering a NULL pointer dereference (Kernel Panic). Fixes: 04e906839a05 ("usbnet: fix cyclical race on disconnect with work queue") Cc: stable@vger.kernel.org Signed-off-by: Ying Lu Link: https://patch.msgid.link/4c9ef2efaa07eb7f9a5042b74348a67e5a3a7aea.1743584159.git.luying1@xiaomi.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

net: usb: usbnet: restore usb%d name exception for local mac addresses

2025-04-07T08:08:36+00:00

commit 2ea396448f26d0d7d66224cb56500a6789c7ed07 upstream. commit 8a7d12d674ac ("net: usb: usbnet: fix name regression") assumed that local addresses always came from the kernel, but some devices hand out local mac addresses so we ended up with point-to-point devices with a mac set by the driver, renaming to eth%d when they used to be named usb%d. Userspace should not rely on device name, but for the sake of stability restore the local mac address check portion of the naming exception: point to point devices which either have no mac set by the driver or have a local mac handed out by the driver will keep the usb%d name. (some USB LTE modems are known to hand out a stable mac from the locally administered range; that mac appears to be random (different for mulitple devices) and can be reset with device-specific commands, so while such devices would benefit from getting a OUI reserved, we have to deal with these and might as well preserve the existing behavior to avoid breaking fragile openwrt configurations and such on upgrade.) Link: https://lkml.kernel.org/r/20241203130457.904325-1-asmadeus@codewreck.org Fixes: 8a7d12d674ac ("net: usb: usbnet: fix name regression") Cc: stable@vger.kernel.org Tested-by: Ahmed Naseef Signed-off-by: Dominique Martinet Acked-by: Oliver Neukum Link: https://patch.msgid.link/20250326-usbnet_rename-v2-1-57eb21fcff26@atmark-techno.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

net: usb: usbnet: fix name regression

2024-10-22T11:24:26+00:00

The fix for MAC addresses broke detection of the naming convention because it gave network devices no random MAC before bind() was called. This means that the check for the local assignment bit was always negative as the address was zeroed from allocation, instead of from overwriting the MAC with a unique hardware address. The correct check for whether bind() has altered the MAC is done with is_zero_ether_addr Signed-off-by: Oliver Neukum Reported-by: Greg Thelen Diagnosed-by: John Sperbeck Fixes: bab8eb0dd4cb9 ("usbnet: modern method to get random MAC") Link: https://patch.msgid.link/20241017071849.389636-1-oneukum@suse.com Signed-off-by: Paolo Abeni

net: usb: usbnet: fix race in probe failure

2024-10-15T09:37:25+00:00

The same bug as in the disconnect code path also exists in the case of a failure late during the probe process. The flag must also be set. Signed-off-by: Oliver Neukum Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Link: https://patch.msgid.link/20241010131934.1499695-1-oneukum@suse.com Signed-off-by: Paolo Abeni