In the Linux kernel, the following vulnerability has been resolved:
ext4: allow ext4_get_group_info() to fail
Previously, ext4_get_group_info() would treat an invalid group number as BUG(), since in theory it should never happen. However, if a malicious attaker (or fuzzer) modifies the superblock via the block device while it is the file system is mounted, it is possible for s_first_data_block to get set to a very large number. In that case, when calculating the block group of some block number (such as the starting block of a preallocation region), could result in an underflow and very large block group number. Then the BUG_ON check in ext4_get_group_info() would fire, resutling in a denial of service attack that can be triggered by root or someone with write access to the block device.
For a quality of implementation perspective, it's best that even if the system administrator does something that they shouldn't, that it will not trigger a BUG. So instead of BUG'ing, ext4_get_group_info() will call ext4_error and return NULL. We also add fallback code in all of the callers of ext4_get_group_info() that it might NULL.
Also, since ext4_get_group_info() was already borderline to be an inline function, un-inline it. The results in a next reduction of the compiled text size of ext4 by roughly 2k.
CVSS Details
- CVSS 3.1 Base Score: 5.5
- CVSS 3.1 Vector: (CVSS:3.1/AV:L/AC:L/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 kernel-headersUpgrade kernel-livepatch-5.15.117-72.142Upgrade perf-debuginfoUpgrade kernel-livepatch-5.10.184-174.730Upgrade bpftool-debuginfoUpgrade kernel-toolsUpgrade python-perfUpgrade python-perf-debuginfoUpgrade kernel-debuginfo-common-x86_64Upgrade kernel-tools-develUpgrade kernel-debuginfoUpgrade perfUpgrade kernel-debuginfo-common-aarch64Upgrade kernelUpgrade bpftoolUpgrade kernel-develUpgrade kernel-tools-debuginfo | May 20, 2026 | May 20, 2026 |
| Amazon_linux_2023 | — | Upgrade kernel-develUpgrade bpftool-debuginfoUpgrade kernel-toolsUpgrade perf-debuginfoUpgrade kernel-debuginfo-common-aarch64Upgrade perfUpgrade kernel-tools-develUpgrade kernel-debuginfoUpgrade kernelUpgrade kernel-libbpf-develUpgrade python3-perf-debuginfoUpgrade kernel-debuginfo-common-x86_64Upgrade kernel-headersUpgrade kernel-livepatch-6.1.34-56.100Upgrade kernel-libbpf-staticUpgrade kernel-libbpfUpgrade bpftoolUpgrade kernel-tools-debuginfoUpgrade python3-perf | Oct 16, 2025 | Oct 1, 2025 |
| Debian | — | Upgrade linux | Oct 3, 2025 | Oct 3, 2025 |
| Huawei Euleros 2_0_sp13 | — | Upgrade kernelUpgrade python3-perfUpgrade kernel-toolsUpgrade kernel-abi-stablelistsUpgrade bpftoolUpgrade kernel-tools-libs | Dec 12, 2025 | Dec 11, 2025 |
| Redhat_linux | — | Upgrade kernel-rtUpgrade kernelNo solution exists | Nov 14, 2025 | Oct 1, 2025 |
| Ubuntu | — | Upgrade linux-gkeopUpgrade linux-gkeUpgrade linux-gcpUpgrade linux-nvidia-tegra-igxUpgrade linux-nvidia-tegraUpgrade linux-riscv-5.15Upgrade linuxUpgrade linux-ibm-5.15Upgrade linux-awsUpgrade linux-nvidia-tegra-5.15Upgrade linux-azure-fde-5.15Upgrade linux-intel-iot-realtimeUpgrade linux-kvmUpgrade linux-hwe-5.15Upgrade linux-oracleUpgrade linux-azureUpgrade linux-oracle-5.15Upgrade linux-aws-5.15Upgrade linux-nvidiaUpgrade linux-lowlatencyUpgrade linux-azure-5.15Upgrade linux-ibmUpgrade linux-xilinx-zynqmpUpgrade linux-gcp-5.15Upgrade linux-realtimeUpgrade linux-lowlatency-hwe-5.15Upgrade linux-intel-iotg-5.15Upgrade linux-bluefieldUpgrade linux-raspiUpgrade linux-intel-iotg | Oct 10, 2025 | Oct 1, 2025 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | Oct 15, 2025 | Oct 1, 2025 |
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