In the Linux kernel, the following vulnerability has been resolved:
net: caif: Fix use-after-free in cfusbl_device_notify()
syzbot reported use-after-free in cfusbl_device_notify() [1]. This causes a stack trace like below:
BUG: KASAN: use-after-free in cfusbl_device_notify+0x7c9/0x870 net/caif/caif_usb.c:138 Read of size 8 at addr ffff88807ac4e6f0 by task kworker/u4:6/1214
CPU: 0 PID: 1214 Comm: kworker/u4:6 Not tainted 5.19.0-rc3-syzkaller-00146-g92f20ff72066 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: netns cleanup_net Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_address_description.constprop.0.cold+0xeb/0x467 mm/kasan/report.c:313 print_report mm/kasan/report.c:429 [inline] kasan_report.cold+0xf4/0x1c6 mm/kasan/report.c:491 cfusbl_device_notify+0x7c9/0x870 net/caif/caif_usb.c:138 notifier_call_chain+0xb5/0x200 kernel/notifier.c:87 call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:1945 call_netdevice_notifiers_extack net/core/dev.c:1983 [inline] call_netdevice_notifiers net/core/dev.c:1997 [inline] netdev_wait_allrefs_any net/core/dev.c:10227 [inline] netdev_run_todo+0xbc0/0x10f0 net/core/dev.c:10341 default_device_exit_batch+0x44e/0x590 net/core/dev.c:11334 ops_exit_list+0x125/0x170 net/core/net_namespace.c:167 cleanup_net+0x4ea/0xb00 net/core/net_namespace.c:594 process_one_work+0x996/0x1610 kernel/workqueue.c:2289 worker_thread+0x665/0x1080 kernel/workqueue.c:2436 kthread+0x2e9/0x3a0 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302 </TASK>
When unregistering a net device, unregister_netdevice_many_notify() sets the device's reg_state to NETREG_UNREGISTERING, calls notifiers with NETDEV_UNREGISTER, and adds the device to the todo list.
Later on, devices in the todo list are processed by netdev_run_todo(). netdev_run_todo() waits devices' reference count become 1 while rebdoadcasting NETDEV_UNREGISTER notification.
When cfusbl_device_notify() is called with NETDEV_UNREGISTER multiple times, the parent device might be freed. This could cause UAF. Processing NETDEV_UNREGISTER multiple times also causes inbalance of reference count for the module.
This patch fixes the issue by accepting only first NETDEV_UNREGISTER notification.
CVSS Details
- CVSS 3.1 Base Score: 7.8
- CVSS 3.1 Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Debian | — | Upgrade linux | May 5, 2025 | May 2, 2025 |
| Ubuntu | — | Upgrade linux-intel-iot-realtimeUpgrade linux-gcpUpgrade linux-lowlatencyUpgrade linux-hwe-5.4Upgrade linux-azure-5.15Upgrade linux-riscv-5.15Upgrade linux-nvidiaUpgrade linux-nvidia-tegra-igxUpgrade linux-aws-fipsUpgrade linux-intel-iotg-5.15Upgrade linux-intel-iotgUpgrade linux-xilinx-zynqmpUpgrade linux-gkeopUpgrade linux-gcp-5.15Upgrade linux-oracleUpgrade linux-azureUpgrade linux-iotUpgrade linux-gcp-fipsUpgrade linux-azure-5.4Upgrade linux-kvmUpgrade linux-ibmUpgrade linux-fipsUpgrade linux-oracle-5.15Upgrade linux-azure-fipsUpgrade linux-gcp-5.4Upgrade linux-hwe-5.15Upgrade linux-aws-5.15Upgrade linux-gkeUpgrade linux-aws-5.4Upgrade linux-nvidia-tegra-5.15Upgrade linux-ibm-5.15Upgrade linux-ibm-5.4Upgrade linux-lowlatency-hwe-5.15Upgrade linux-oracle-5.4Upgrade linux-bluefieldUpgrade linux-nvidia-tegraUpgrade linux-realtimeUpgrade linuxUpgrade linux-raspiUpgrade linux-raspi-5.4Upgrade linux-awsUpgrade linux-azure-fde | May 8, 2025 | May 2, 2025 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | May 27, 2026 | May 2, 2025 |
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