In the Linux kernel, the following vulnerability has been resolved:
blk-iocost: fix divide by 0 error in calc_lcoefs()
echo max of u64 to cost.model can cause divide by 0 error.
# echo 8:0 rbps=18446744073709551615 > /sys/fs/cgroup/io.cost.model
divide error: 0000 [#1] PREEMPT SMP RIP: 0010:calc_lcoefs+0x4c/0xc0 Call Trace: <TASK> ioc_refresh_params+0x2b3/0x4f0 ioc_cost_model_write+0x3cb/0x4c0 ? _copy_from_iter+0x6d/0x6c0 ? kernfs_fop_write_iter+0xfc/0x270 cgroup_file_write+0xa0/0x200 kernfs_fop_write_iter+0x17d/0x270 vfs_write+0x414/0x620 ksys_write+0x73/0x160 __x64_sys_write+0x1e/0x30 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x63/0xcd
calc_lcoefs() uses the input value of cost.model in DIV_ROUND_UP_ULL, overflow would happen if bps plus IOC_PAGE_SIZE is greater than ULLONG_MAX, it can cause divide by 0 error.
Fix the problem by setting basecost
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon Linux Ami 2 | — | Upgrade kernel-tools-develUpgrade kernel-livepatch-5.10.173-154.642Upgrade kernel-debuginfoUpgrade kernelUpgrade perfUpgrade kernel-tools-debuginfoUpgrade kernel-debuginfo-common-aarch64Upgrade perf-debuginfoUpgrade kernel-develUpgrade bpftoolUpgrade kernel-headersUpgrade python-perf-debuginfoUpgrade kernel-toolsUpgrade bpftool-debuginfoUpgrade python-perfUpgrade kernel-livepatch-5.15.102-61.139Upgrade kernel-debuginfo-common-x86_64 | May 20, 2026 | May 20, 2026 |
| Amazon_linux_2023 | — | Upgrade kernel-toolsUpgrade kernel-develUpgrade bpftool-debuginfoUpgrade bpftoolUpgrade kernel-livepatch-6.1.19-30.43Upgrade kernel-debuginfo-common-x86_64Upgrade python3-perf-debuginfoUpgrade kernel-libbpf-develUpgrade kernelUpgrade kernel-libbpf-staticUpgrade kernel-headersUpgrade kernel-debuginfo-common-aarch64Upgrade kernel-tools-develUpgrade python3-perfUpgrade perfUpgrade kernel-tools-debuginfoUpgrade perf-debuginfoUpgrade kernel-libbpfUpgrade kernel-debuginfo | Jan 12, 2026 | Dec 9, 2025 |
| Debian | — | Upgrade linux | Dec 10, 2025 | Dec 10, 2025 |
| Huawei Euleros 2_0_sp13 | — | Upgrade kernel-toolsUpgrade kernel-abi-stablelistsUpgrade kernel-tools-libsUpgrade bpftoolUpgrade kernelUpgrade python3-perf | Mar 10, 2026 | Mar 10, 2026 |
| Redhat_linux | — | No solution exists | Jul 17, 2026 | Dec 9, 2025 |
| Ubuntu | — | Upgrade linux-hwe-5.15Upgrade linux-gcp-fipsUpgrade linux-azure-5.4Upgrade linux-iotUpgrade linux-lowlatency-hwe-5.15Upgrade linux-bluefieldUpgrade linuxUpgrade linux-ibm-5.4Upgrade linux-nvidia-tegraUpgrade linux-nvidia-tegra-5.15Upgrade linux-raspi-5.4Upgrade linux-aws-5.15Upgrade linux-awsUpgrade linux-oracle-5.15Upgrade linux-intel-iot-realtimeUpgrade linux-fipsUpgrade linux-kvmUpgrade linux-gkeopUpgrade linux-xilinx-zynqmpUpgrade linux-lowlatencyUpgrade linux-gkeUpgrade linux-azure-fipsUpgrade linux-hwe-5.4Upgrade linux-aws-5.4Upgrade linux-gcp-5.4Upgrade linux-azureUpgrade linux-gcpUpgrade linux-aws-fipsUpgrade linux-intel-iotgUpgrade linux-azure-5.15Upgrade linux-gcp-5.15Upgrade linux-nvidiaUpgrade linux-azure-fde-5.15Upgrade linux-realtimeUpgrade linux-oracle-5.4Upgrade linux-oracleUpgrade linux-raspiUpgrade linux-intel-iotg-5.15Upgrade linux-ibmUpgrade linux-riscv-5.15 | Dec 11, 2025 | Dec 9, 2025 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | May 27, 2026 | Dec 9, 2025 |
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