In the Linux kernel, the following vulnerability has been resolved:
jfs: jfs_dmap: Validate db_l2nbperpage while mounting
In jfs_dmap.c at line 381, BLKTODMAP is used to get a logical block number inside dbFree(). db_l2nbperpage, which is the log2 number of blocks per page, is passed as an argument to BLKTODMAP which uses it for shifting.
Syzbot reported a shift out-of-bounds crash because db_l2nbperpage is too big. This happens because the large value is set without any validation in dbMount() at line 181.
Thus, make sure that db_l2nbperpage is correct while mounting.
Max number of blocks per page = Page size / Min block size => log2(Max num_block per page) = log2(Page size / Min block size) = log2(Page size) - log2(Min block size)
=> Max db_l2nbperpage = L2PSIZE - L2MINBLOCKSIZE
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon Linux Ami 2 | — | Upgrade kernelUpgrade python-perfUpgrade bpftoolUpgrade kernel-tools-debuginfoUpgrade bpftool-debuginfoUpgrade python-perf-debuginfoUpgrade kernel-livepatch-5.10.192-182.736Upgrade kernel-debuginfo-common-x86_64Upgrade kernel-develUpgrade perfUpgrade kernel-debuginfo-common-aarch64Upgrade kernel-toolsUpgrade kernel-tools-develUpgrade kernel-headersUpgrade kernel-debuginfoUpgrade kernel-livepatch-4.14.322-244.536Upgrade perf-debuginfo | May 20, 2026 | May 20, 2026 |
| Debian | — | Upgrade linux | Sep 17, 2025 | Sep 17, 2025 |
| Redhat_linux | — | No solution exists | Jul 17, 2026 | Sep 15, 2025 |
| Ubuntu | — | Upgrade linux-lowlatency-hwe-5.15Upgrade linux-oracle-5.15Upgrade linux-azure-fipsUpgrade linux-azure-5.15Upgrade linux-azure-fdeUpgrade linux-azure-fde-5.15Upgrade linux-fipsUpgrade linux-ibm-5.15Upgrade linux-lowlatencyUpgrade linux-raspiUpgrade linux-intel-iot-realtimeUpgrade linux-gkeopUpgrade linux-nvidia-tegra-5.15Upgrade linux-nvidia-tegraUpgrade linux-nvidiaUpgrade linux-kvmUpgrade linux-aws-5.4Upgrade linux-oracle-5.4Upgrade linux-gcpUpgrade linux-intel-iotgUpgrade linux-aws-5.15Upgrade linux-gkeUpgrade linux-riscv-5.15Upgrade linux-xilinx-zynqmpUpgrade linux-gcp-5.15Upgrade linux-oracleUpgrade linux-realtimeUpgrade linux-aws-fipsUpgrade linux-gcp-5.4Upgrade linux-ibm-5.4Upgrade linux-raspi-5.4Upgrade linux-nvidia-tegra-igxUpgrade linux-hwe-5.15Upgrade linux-bluefieldUpgrade linux-azureUpgrade linuxUpgrade linux-iotUpgrade linux-gcp-fipsUpgrade linux-intel-iotg-5.15Upgrade linux-azure-5.4Upgrade linux-hwe-5.4Upgrade linux-ibmUpgrade linux-aws | Sep 19, 2025 | Sep 16, 2025 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | Oct 15, 2025 | Sep 15, 2025 |
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