In the Linux kernel, the following vulnerability has been resolved:
ext4: block range must be validated before use in ext4_mb_clear_bb()
Block range to free is validated in ext4_free_blocks() using ext4_inode_block_valid() and then it's passed to ext4_mb_clear_bb(). However in some situations on bigalloc file system the range might be adjusted after the validation in ext4_free_blocks() which can lead to troubles on corrupted file systems such as one found by syzkaller that resulted in the following BUG
kernel BUG at fs/ext4/ext4.h:3319! PREEMPT SMP NOPTI CPU: 28 PID: 4243 Comm: repro Kdump: loaded Not tainted 5.19.0-rc6+ #1 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1.fc35 04/01/2014 RIP: 0010:ext4_free_blocks+0x95e/0xa90 Call Trace: <TASK> ? lock_timer_base+0x61/0x80 ? __es_remove_extent+0x5a/0x760 ? __mod_timer+0x256/0x380 ? ext4_ind_truncate_ensure_credits+0x90/0x220 ext4_clear_blocks+0x107/0x1b0 ext4_free_data+0x15b/0x170 ext4_ind_truncate+0x214/0x2c0 ? _raw_spin_unlock+0x15/0x30 ? ext4_discard_preallocations+0x15a/0x410 ? ext4_journal_check_start+0xe/0x90 ? __ext4_journal_start_sb+0x2f/0x110 ext4_truncate+0x1b5/0x460 ? __ext4_journal_start_sb+0x2f/0x110 ext4_evict_inode+0x2b4/0x6f0 evict+0xd0/0x1d0 ext4_enable_quotas+0x11f/0x1f0 ext4_orphan_cleanup+0x3de/0x430 ? proc_create_seq_private+0x43/0x50 ext4_fill_super+0x295f/0x3ae0 ? snprintf+0x39/0x40 ? sget_fc+0x19c/0x330 ? ext4_reconfigure+0x850/0x850 get_tree_bdev+0x16d/0x260 vfs_get_tree+0x25/0xb0 path_mount+0x431/0xa70 __x64_sys_mount+0xe2/0x120 do_syscall_64+0x5b/0x80 ? do_user_addr_fault+0x1e2/0x670 ? exc_page_fault+0x70/0x170 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x7fdf4e512ace
Fix it by making sure that the block range is properly validated before used every time it changes in ext4_free_blocks() or ext4_mb_clear_bb().
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon Linux Ami 2 | — | Upgrade kernel-headersUpgrade kernel-debuginfo-common-aarch64Upgrade kernel-livepatch-5.10.176-157.645Upgrade kernel-livepatch-5.15.104-63.140Upgrade perfUpgrade python-perf-debuginfoUpgrade kernel-debuginfoUpgrade perf-debuginfoUpgrade kernel-tools-develUpgrade kernel-tools-debuginfoUpgrade bpftoolUpgrade kernel-toolsUpgrade kernel-debuginfo-common-x86_64Upgrade kernelUpgrade kernel-develUpgrade python-perfUpgrade bpftool-debuginfo | May 20, 2026 | May 20, 2026 |
| Debian | — | Upgrade linux | Jun 20, 2025 | Jun 20, 2025 |
| Dell Powerstore Dsa2025429 | — | Upgrade Dell PowerStoreOS to the latest version | Dec 3, 2025 | Dec 2, 2025 |
| Dell Powerstore Dsa2026039 | — | Upgrade Dell PowerStoreOS to the latest version | Jan 13, 2026 | Jan 6, 2026 |
| Huawei Euleros 2_0_sp13 | — | Upgrade kernel-abi-stablelistsUpgrade python3-perfUpgrade kernel-tools-libsUpgrade kernel-toolsUpgrade kernelUpgrade bpftool | Oct 24, 2025 | Oct 23, 2025 |
| Redhat_linux | — | No solution exists | Jul 9, 2025 | Jun 18, 2025 |
| Ubuntu | — | Upgrade linux-azure-fdeUpgrade linux-lowlatency-hwe-5.15Upgrade linux-realtimeUpgrade linux-aws-5.15Upgrade linux-nvidia-tegra-5.15Upgrade linux-kvmUpgrade linux-hwe-5.15Upgrade linux-raspiUpgrade linux-gkeUpgrade linux-lowlatencyUpgrade linux-intel-iotgUpgrade linux-azureUpgrade linux-intel-iotg-5.15Upgrade linux-gcp-5.15Upgrade linux-bluefieldUpgrade linux-awsUpgrade linux-nvidia-tegraUpgrade linux-intel-iot-realtimeUpgrade linux-gkeopUpgrade linux-ibmUpgrade linux-riscv-5.15Upgrade linux-oracleUpgrade linux-xilinx-zynqmpUpgrade linux-oracle-5.15Upgrade linux-azure-5.15Upgrade linuxUpgrade linux-nvidia-tegra-igxUpgrade linux-ibm-5.15Upgrade linux-gcpUpgrade linux-nvidia | Jun 26, 2025 | Jun 18, 2025 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | May 27, 2026 | Jun 18, 2025 |
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