In the Linux kernel, the following vulnerability has been resolved:
net: tun: Fix use-after-free in tun_detach()
syzbot reported use-after-free in tun_detach() [1]. This causes call trace like below:
================================================================== BUG: KASAN: use-after-free in notifier_call_chain+0x1ee/0x200 kernel/notifier.c:75 Read of size 8 at addr ffff88807324e2a8 by task syz-executor.0/3673
CPU: 0 PID: 3673 Comm: syz-executor.0 Not tainted 6.1.0-rc5-syzkaller-00044-gcc675d22e422 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:284 [inline] print_report+0x15e/0x461 mm/kasan/report.c:395 kasan_report+0xbf/0x1f0 mm/kasan/report.c:495 notifier_call_chain+0x1ee/0x200 kernel/notifier.c:75 call_netdevice_notifiers_info+0x86/0x130 net/core/dev.c:1942 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:10237 [inline] netdev_run_todo+0xbc6/0x1100 net/core/dev.c:10351 tun_detach drivers/net/tun.c:704 [inline] tun_chr_close+0xe4/0x190 drivers/net/tun.c:3467 __fput+0x27c/0xa90 fs/file_table.c:320 task_work_run+0x16f/0x270 kernel/task_work.c:179 exit_task_work include/linux/task_work.h:38 [inline] do_exit+0xb3d/0x2a30 kernel/exit.c:820 do_group_exit+0xd4/0x2a0 kernel/exit.c:950 get_signal+0x21b1/0x2440 kernel/signal.c:2858 arch_do_signal_or_restart+0x86/0x2300 arch/x86/kernel/signal.c:869 exit_to_user_mode_loop kernel/entry/common.c:168 [inline] exit_to_user_mode_prepare+0x15f/0x250 kernel/entry/common.c:203 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline] syscall_exit_to_user_mode+0x1d/0x50 kernel/entry/common.c:296 do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x63/0xcd
The cause of the issue is that sock_put() from __tun_detach() drops last reference count for struct net, and then notifier_call_chain() from netdev_state_change() accesses that struct net.
This patch fixes the issue by calling sock_put() from tun_detach() after all necessary accesses for the struct net has done.
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon Linux Ami 2 | — | Upgrade perf-debuginfoUpgrade bpftoolUpgrade kernel-develUpgrade kernel-livepatch-5.10.162-141.675Upgrade kernel-debuginfoUpgrade kernel-debuginfo-common-aarch64Upgrade kernel-tools-debuginfoUpgrade kernel-livepatch-5.15.86-53.137Upgrade kernel-tools-develUpgrade perfUpgrade kernel-toolsUpgrade kernelUpgrade python-perfUpgrade python-perf-debuginfoUpgrade bpftool-debuginfoUpgrade kernel-debuginfo-common-x86_64Upgrade kernel-headers | Jan 22, 2025 | Oct 21, 2024 |
| Debian | — | Upgrade linux | Oct 23, 2024 | Oct 23, 2024 |
| Dell Powerstore Dsa2025223 | — | Upgrade Dell PowerStoreOS to the latest version | Oct 23, 2025 | May 27, 2025 |
| Huawei Euleros 2_0_sp12 | — | Upgrade kernel-abi-stablelistsUpgrade kernel-toolsUpgrade kernelUpgrade python3-perfUpgrade kernel-tools-libsUpgrade bpftool | Feb 11, 2025 | Oct 21, 2024 |
| Huawei Euleros 2_0_sp9 | — | Upgrade kernel-tools-libsUpgrade python3-perfUpgrade kernel-toolsUpgrade kernel | Jan 15, 2025 | Oct 21, 2024 |
| Redhat_linux | — | Upgrade kernelUpgrade kernel-rtNo solution exists | May 15, 2025 | Oct 21, 2024 |
| Ubuntu | — | Upgrade linux-intel-iot-realtimeUpgrade linux-nvidiaUpgrade linux-aws-fipsUpgrade linux-lowlatencyUpgrade linux-xilinx-zynqmpUpgrade linux-realtimeUpgrade linux-kvmUpgrade linux-azure-5.15Upgrade linux-ibmUpgrade linux-aws-5.15Upgrade linux-gkeopUpgrade linux-gcpUpgrade linux-aws-5.4Upgrade linux-raspiUpgrade linux-oracle-5.15Upgrade linux-fipsUpgrade linux-intel-iotg-5.15Upgrade linux-gkeUpgrade linux-hwe-5.4Upgrade linux-azure-fdeUpgrade linux-gcp-5.15Upgrade linux-intel-iotgUpgrade linux-oracle-5.4Upgrade linux-riscv-5.15Upgrade linux-gcp-5.4Upgrade linux-oracleUpgrade linux-azure-fipsUpgrade linux-ibm-5.4Upgrade linux-bluefieldUpgrade linux-nvidia-tegra-5.15Upgrade linux-gkeop-5.15Upgrade linux-raspi-5.4Upgrade linux-iotUpgrade linuxUpgrade linux-azureUpgrade linux-hwe-5.15Upgrade linux-gcp-fipsUpgrade linux-azure-5.4Upgrade linux-lowlatency-hwe-5.15Upgrade linux-aws | Nov 19, 2024 | Oct 21, 2024 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | May 27, 2026 | Oct 21, 2024 |
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