In the Linux kernel, the following vulnerability has been resolved:
mrp: introduce active flags to prevent UAF when applicant uninit
The caller of del_timer_sync must prevent restarting of the timer, If we have no this synchronization, there is a small probability that the cancellation will not be successful.
And syzbot report the fellowing crash: ================================================================== BUG: KASAN: use-after-free in hlist_add_head include/linux/list.h:929 [inline] BUG: KASAN: use-after-free in enqueue_timer+0x18/0xa4 kernel/time/timer.c:605 Write at addr f9ff000024df6058 by task syz-fuzzer/2256 Pointer tag: [f9], memory tag: [fe]
CPU: 1 PID: 2256 Comm: syz-fuzzer Not tainted 6.1.0-rc5-syzkaller-00008- ge01d50cbd6ee #0 Hardware name: linux,dummy-virt (DT) Call trace: dump_backtrace.part.0+0xe0/0xf0 arch/arm64/kernel/stacktrace.c:156 dump_backtrace arch/arm64/kernel/stacktrace.c:162 [inline] show_stack+0x18/0x40 arch/arm64/kernel/stacktrace.c:163 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x68/0x84 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:284 [inline] print_report+0x1a8/0x4a0 mm/kasan/report.c:395 kasan_report+0x94/0xb4 mm/kasan/report.c:495 __do_kernel_fault+0x164/0x1e0 arch/arm64/mm/fault.c:320 do_bad_area arch/arm64/mm/fault.c:473 [inline] do_tag_check_fault+0x78/0x8c arch/arm64/mm/fault.c:749 do_mem_abort+0x44/0x94 arch/arm64/mm/fault.c:825 el1_abort+0x40/0x60 arch/arm64/kernel/entry-common.c:367 el1h_64_sync_handler+0xd8/0xe4 arch/arm64/kernel/entry-common.c:427 el1h_64_sync+0x64/0x68 arch/arm64/kernel/entry.S:576 hlist_add_head include/linux/list.h:929 [inline] enqueue_timer+0x18/0xa4 kernel/time/timer.c:605 mod_timer+0x14/0x20 kernel/time/timer.c:1161 mrp_periodic_timer_arm net/802/mrp.c:614 [inline] mrp_periodic_timer+0xa0/0xc0 net/802/mrp.c:627 call_timer_fn.constprop.0+0x24/0x80 kernel/time/timer.c:1474 expire_timers+0x98/0xc4 kernel/time/timer.c:1519
To fix it, we can introduce a new active flags to make sure the timer will not restart.
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 |
|---|---|---|---|---|
| Amazon Linux Ami 2 | — | Upgrade kernel-livepatch-4.14.304-226.531Upgrade kernel-livepatch-5.15.86-53.137Upgrade kernel-toolsUpgrade kernel-debuginfo-common-aarch64Upgrade python-perfUpgrade bpftool-debuginfoUpgrade kernel-livepatch-5.10.165-143.735Upgrade perfUpgrade bpftoolUpgrade kernel-develUpgrade kernelUpgrade perf-debuginfoUpgrade python-perf-debuginfoUpgrade kernel-debuginfo-common-x86_64Upgrade kernel-tools-develUpgrade kernel-debuginfoUpgrade kernel-tools-debuginfoUpgrade kernel-headers | May 20, 2026 | May 20, 2026 |
| Debian | — | Upgrade linux | Dec 29, 2025 | Dec 29, 2025 |
| Huawei Euleros 2_0_sp13 | — | Upgrade bpftoolUpgrade kernelUpgrade python3-perfUpgrade kernel-toolsUpgrade kernel-abi-stablelistsUpgrade kernel-tools-libs | Mar 10, 2026 | Mar 10, 2026 |
| Redhat_linux | — | No solution exists | Jul 17, 2026 | Dec 24, 2025 |
| Ubuntu | — | Upgrade linux-ibm-5.4Upgrade linux-gkeopUpgrade linux-gcp-fipsUpgrade linux-intel-iot-realtimeUpgrade linux-gcp-5.4Upgrade linux-aws-fipsUpgrade linux-intel-iotgUpgrade linux-riscv-5.15Upgrade linux-azure-fipsUpgrade linux-azure-5.15Upgrade linux-nvidia-tegra-5.15Upgrade linux-hwe-5.4Upgrade linux-hweUpgrade linuxUpgrade linux-fipsUpgrade linux-gcpUpgrade linux-ibmUpgrade linux-gcp-4.15Upgrade linux-kvmUpgrade linux-bluefieldUpgrade linux-gkeUpgrade linux-azureUpgrade linux-oracle-5.4Upgrade linux-aws-5.15Upgrade linux-awsUpgrade linux-azure-fdeUpgrade linux-raspiUpgrade linux-realtimeUpgrade linux-oracleUpgrade linux-nvidiaUpgrade linux-azure-5.4Upgrade linux-aws-5.4Upgrade linux-azure-4.15Upgrade linux-raspi-5.4Upgrade linux-aws-hweUpgrade linux-gcp-5.15Upgrade linux-lowlatency-hwe-5.15Upgrade linux-intel-iotg-5.15Upgrade linux-iotUpgrade linux-xilinx-zynqmpUpgrade linux-lowlatencyUpgrade linux-hwe-5.15Upgrade linux-oracle-5.15 | Jan 6, 2026 | Dec 24, 2025 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | May 27, 2026 | Dec 24, 2025 |
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