kernel.git/drivers/net/usb/usbnet.c, branch linux-5.10.y

usbnet: limit max_mtu based on device's hard_mtu

2026-02-06T15:40:06Z

[ 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: Prevents free active kevent

2025-12-06T21:08:07Z

[ 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

2025-08-28T14:22:58Z

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

2025-08-28T14:22:53Z

[ Upstream commit 0d9cfc9b8cb17dbc29a98792d36ec39a1cf1395f ] 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 [ adjust context in header ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

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

2025-04-10T12:30:54Z

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

2024-11-08T15:21:59Z

[ Upstream commit 8a7d12d674ac6f2147c18f36d1e15f1a48060edf ] 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 Signed-off-by: Sasha Levin

usbnet: modern method to get random MAC

2024-09-12T09:06:47Z

[ Upstream commit bab8eb0dd4cb995caa4a0529d5655531c2ec5e8e ] The driver generates a random MAC once on load and uses it over and over, including on two devices needing a random MAC at the same time. Jakub suggested revamping the driver to the modern API for setting a random MAC rather than fixing the old stuff. The bug is as old as the driver. Signed-off-by: Oliver Neukum Reviewed-by: Simon Horman Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Link: https://patch.msgid.link/20240829175201.670718-1-oneukum@suse.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net: usb: don't write directly to netdev->dev_addr

2024-09-12T09:06:47Z

[ Upstream commit 2674e7ea22ba0e22a2d1603bd51e0b8f6442a267 ] Commit 406f42fa0d3c ("net-next: When a bond have a massive amount of VLANs...") introduced a rbtree for faster Ethernet address look up. To maintain netdev->dev_addr in this tree we need to make all the writes to it got through appropriate helpers. Manually fix all net/usb drivers without separate maintainers. v2: catc does DMA to the buffer, leave the conversion to Oliver Signed-off-by: Jakub Kicinski Stable-dep-of: bab8eb0dd4cb ("usbnet: modern method to get random MAC") Signed-off-by: Sasha Levin

drivers/net/usb: Remove all strcpy() uses

2024-09-12T09:06:47Z

[ Upstream commit 493c3ca6bd754d8587604496eb814f72e933075d ] strcpy() performs no bounds checking on the destination buffer. This could result in linear overflows beyond the end of the buffer, leading to all kinds of misbehaviors. The safe replacement is strscpy(). Signed-off-by: Len Baker Signed-off-by: David S. Miller Stable-dep-of: bab8eb0dd4cb ("usbnet: modern method to get random MAC") Signed-off-by: Sasha Levin

net: usbnet: Fix WARNING in usbnet_start_xmit/usb_submit_urb

2023-08-11T09:57:53Z

commit 5e1627cb43ddf1b24b92eb26f8d958a3f5676ccb upstream. The syzbot fuzzer identified a problem in the usbnet driver: usb 1-1: BOGUS urb xfer, pipe 3 != type 1 WARNING: CPU: 0 PID: 754 at drivers/usb/core/urb.c:504 usb_submit_urb+0xed6/0x1880 drivers/usb/core/urb.c:504 Modules linked in: CPU: 0 PID: 754 Comm: kworker/0:2 Not tainted 6.4.0-rc7-syzkaller-00014-g692b7dc87ca6 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023 Workqueue: mld mld_ifc_work RIP: 0010:usb_submit_urb+0xed6/0x1880 drivers/usb/core/urb.c:504 Code: 7c 24 18 e8 2c b4 5b fb 48 8b 7c 24 18 e8 42 07 f0 fe 41 89 d8 44 89 e1 4c 89 ea 48 89 c6 48 c7 c7 a0 c9 fc 8a e8 5a 6f 23 fb <0f> 0b e9 58 f8 ff ff e8 fe b3 5b fb 48 81 c5 c0 05 00 00 e9 84 f7 RSP: 0018:ffffc9000463f568 EFLAGS: 00010086 RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000000 RDX: ffff88801eb28000 RSI: ffffffff814c03b7 RDI: 0000000000000001 RBP: ffff8881443b7190 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000003 R13: ffff88802a77cb18 R14: 0000000000000003 R15: ffff888018262500 FS: 0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000556a99c15a18 CR3: 0000000028c71000 CR4: 0000000000350ef0 Call Trace: usbnet_start_xmit+0xfe5/0x2190 drivers/net/usb/usbnet.c:1453 __netdev_start_xmit include/linux/netdevice.h:4918 [inline] netdev_start_xmit include/linux/netdevice.h:4932 [inline] xmit_one net/core/dev.c:3578 [inline] dev_hard_start_xmit+0x187/0x700 net/core/dev.c:3594 ... This bug is caused by the fact that usbnet trusts the bulk endpoint addresses its probe routine receives in the driver_info structure, and it does not check to see that these endpoints actually exist and have the expected type and directions. The fix is simply to add such a check. Reported-and-tested-by: syzbot+63ee658b9a100ffadbe2@syzkaller.appspotmail.com Closes: https://lore.kernel.org/linux-usb/000000000000a56e9105d0cec021@google.com/ Signed-off-by: Alan Stern CC: Oliver Neukum Link: https://lore.kernel.org/r/ea152b6d-44df-4f8a-95c6-4db51143dcc1@rowland.harvard.edu Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman