In the Linux kernel, the following vulnerability has been resolved:
tracing: Fix race issue between cpu buffer write and swap
Warning happened in rb_end_commit() at code: if (RB_WARN_ON(cpu_buffer, !local_read(&cpu_buffer->committing)))
WARNING: CPU: 0 PID: 139 at kernel/trace/ring_buffer.c:3142 rb_commit+0x402/0x4a0 Call Trace: ring_buffer_unlock_commit+0x42/0x250 trace_buffer_unlock_commit_regs+0x3b/0x250 trace_event_buffer_commit+0xe5/0x440 trace_event_buffer_reserve+0x11c/0x150 trace_event_raw_event_sched_switch+0x23c/0x2c0 __traceiter_sched_switch+0x59/0x80 __schedule+0x72b/0x1580 schedule+0x92/0x120 worker_thread+0xa0/0x6f0
It is because the race between writing event into cpu buffer and swapping cpu buffer through file per_cpu/cpu0/snapshot:
Write on CPU 0 Swap buffer by per_cpu/cpu0/snapshot on CPU 1 -------- -------- tracing_snapshot_write() [...]
ring_buffer_lock_reserve() cpu_buffer = buffer->buffers[cpu]; // 1. Suppose find 'cpu_buffer_a'; [...] rb_reserve_next_event() [...]
ring_buffer_swap_cpu() if (local_read(&cpu_buffer_a->committing)) goto out_dec; if (local_read(&cpu_buffer_b->committing)) goto out_dec; buffer_a->buffers[cpu] = cpu_buffer_b; buffer_b->buffers[cpu] = cpu_buffer_a; // 2. cpu_buffer has swapped here.
rb_start_commit(cpu_buffer); if (unlikely(READ_ONCE(cpu_buffer->buffer) != buffer)) { // 3. This check passed due to 'cpu_buffer->buffer' [...] // has not changed here. return NULL; } cpu_buffer_b->buffer = buffer_a; cpu_buffer_a->buffer = buffer_b; [...]
// 4. Reserve event from 'cpu_buffer_a'.
ring_buffer_unlock_commit() [...] cpu_buffer = buffer->buffers[cpu]; // 5. Now find 'cpu_buffer_b' !!! rb_commit(cpu_buffer) rb_end_commit() // 6. WARN for the wrong 'committing' state !!!
Based on above analysis, we can easily reproduce by following testcase: ``` bash #!/bin/bash
dmesg -n 7 sysctl -w kernel.panic_on_warn=1 TR=/sys/kernel/tracing echo 7 > ${TR}/buffer_size_kb echo "sched:sched_switch" > ${TR}/set_event while [ true ]; do echo 1 > ${TR}/per_cpu/cpu0/snapshot done & while [ true ]; do echo 1 > ${TR}/per_cpu/cpu0/snapshot done & while [ true ]; do echo 1 > ${TR}/per_cpu/cpu0/snapshot done & ```
To fix it, IIUC, we can use smp_call_function_single() to do the swap on the target cpu where the buffer is located, so that above race would be avoided.
CVSS Details
- CVSS 3.1 Base Score: 4.7
- CVSS 3.1 Vector: (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon Linux Ami 2 | — | Upgrade perfUpgrade kernel-debuginfo-common-aarch64Upgrade kernel-develUpgrade kernel-headersUpgrade kernelUpgrade kernel-tools-develUpgrade perf-debuginfoUpgrade kernel-debuginfoUpgrade bpftool-debuginfoUpgrade kernel-livepatch-5.10.196-185.743Upgrade kernel-livepatch-5.15.133-86.144Upgrade python-perfUpgrade bpftoolUpgrade python-perf-debuginfoUpgrade kernel-toolsUpgrade kernel-debuginfo-common-x86_64Upgrade kernel-tools-debuginfo | May 20, 2026 | May 20, 2026 |
| Amazon_linux_2023 | — | Upgrade kernel-libbpf-staticUpgrade kernel-libbpf-develUpgrade kernel-tools-develUpgrade kernel-tools-debuginfoUpgrade kernel-livepatch-6.1.55-75.123Upgrade kernel-develUpgrade kernel-debuginfo-common-x86_64Upgrade kernelUpgrade kernel-headersUpgrade python3-perfUpgrade kernel-libbpfUpgrade kernel-debuginfoUpgrade bpftoolUpgrade python3-perf-debuginfoUpgrade kernel-debuginfo-common-aarch64Upgrade bpftool-debuginfoUpgrade perf-debuginfoUpgrade kernel-toolsUpgrade perf | Oct 16, 2025 | Sep 17, 2025 |
| Debian | — | Upgrade linux | Sep 19, 2025 | Sep 19, 2025 |
| Huawei Euleros 2_0_sp10 | — | Upgrade kernel-tools-libsUpgrade python3-perfUpgrade kernelUpgrade kernel-toolsUpgrade kernel-abi-stablelists | Jan 15, 2026 | Jan 13, 2026 |
| Huawei Euleros 2_0_sp13 | — | Upgrade bpftoolUpgrade python3-perfUpgrade kernel-abi-stablelistsUpgrade kernel-toolsUpgrade kernel-tools-libsUpgrade kernel | Dec 12, 2025 | Dec 11, 2025 |
| Redhat_linux | — | No solution exists | Jul 17, 2026 | Sep 17, 2025 |
| Ubuntu | — | Upgrade linuxUpgrade linux-azure-fipsUpgrade linux-awsUpgrade linux-ibm-5.4Upgrade linux-lowlatencyUpgrade linux-gkeopUpgrade linux-gcpUpgrade linux-gcp-fipsUpgrade linux-nvidia-tegraUpgrade linux-oracle-5.4Upgrade linux-gcp-5.4Upgrade linux-gkeUpgrade linux-nvidia-tegra-5.15Upgrade linux-intel-iot-realtimeUpgrade linux-nvidia-tegra-igxUpgrade linux-ibm-5.15Upgrade linux-aws-5.15Upgrade linux-azureUpgrade linux-nvidiaUpgrade linux-realtimeUpgrade linux-xilinx-zynqmpUpgrade linux-hwe-5.15Upgrade linux-gcp-5.15Upgrade linux-fipsUpgrade linux-raspi-5.4Upgrade linux-riscv-5.15Upgrade linux-aws-fipsUpgrade linux-aws-5.4Upgrade linux-hwe-5.4Upgrade linux-oracleUpgrade linux-ibmUpgrade linux-oracle-5.15Upgrade linux-bluefieldUpgrade linux-iotUpgrade linux-azure-5.4Upgrade linux-lowlatency-hwe-5.15Upgrade linux-intel-iotg-5.15Upgrade linux-azure-5.15Upgrade linux-raspiUpgrade linux-kvmUpgrade linux-intel-iotg | Sep 26, 2025 | Sep 17, 2025 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | Oct 15, 2025 | Sep 17, 2025 |
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