In the Linux kernel, the following vulnerability has been resolved:
ext4: add reserved GDT blocks check
We capture a NULL pointer issue when resizing a corrupt ext4 image which is freshly clear resize_inode feature (not run e2fsck). It could be simply reproduced by following steps. The problem is because of the resize_inode feature was cleared, and it will convert the filesystem to meta_bg mode in ext4_resize_fs(), but the es->s_reserved_gdt_blocks was not reduced to zero, so could we mistakenly call reserve_backup_gdb() and passing an uninitialized resize_inode to it when adding new group descriptors.
mkfs.ext4 /dev/sda 3G tune2fs -O ^resize_inode /dev/sda #forget to run requested e2fsck mount /dev/sda /mnt resize2fs /dev/sda 8G
======== BUG: kernel NULL pointer dereference, address: 0000000000000028 CPU: 19 PID: 3243 Comm: resize2fs Not tainted 5.18.0-rc7-00001-gfde086c5ebfd #748 ... RIP: 0010:ext4_flex_group_add+0xe08/0x2570 ... Call Trace: <TASK> ext4_resize_fs+0xbec/0x1660 __ext4_ioctl+0x1749/0x24e0 ext4_ioctl+0x12/0x20 __x64_sys_ioctl+0xa6/0x110 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f2dd739617b ========
The fix is simple, add a check in ext4_resize_begin() to make sure that the es->s_reserved_gdt_blocks is zero when the resize_inode feature is disabled.
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 python-perfUpgrade kernel-debuginfo-common-aarch64Upgrade kernel-toolsUpgrade bpftoolUpgrade bpftool-debuginfoUpgrade kernel-debuginfo-common-x86_64Upgrade kernel-livepatch-4.14.285-215.501Upgrade perf-debuginfoUpgrade kernel-livepatch-5.15.50-23.125Upgrade kernelUpgrade kernel-livepatch-5.10.126-117.518Upgrade kernel-tools-develUpgrade python-perf-debuginfoUpgrade kernel-debuginfoUpgrade kernel-develUpgrade kernel-headersUpgrade perfUpgrade kernel-tools-debuginfo | May 21, 2025 | Feb 26, 2025 |
| Debian | — | Upgrade linux | Feb 27, 2025 | Feb 27, 2025 |
| Huawei Euleros 2_0_sp12 | — | Upgrade kernel-abi-stablelistsUpgrade kernelUpgrade python3-perfUpgrade bpftoolUpgrade kernel-toolsUpgrade kernel-tools-libs | Jun 11, 2025 | Feb 26, 2025 |
| Huawei Euleros 2_0_sp13 | — | Upgrade kernel-abi-stablelistsUpgrade python3-perfUpgrade kernelUpgrade kernel-toolsUpgrade kernel-tools-libsUpgrade bpftool | Jun 11, 2025 | Feb 26, 2025 |
| Redhat_linux | — | No solution exists | Jul 9, 2025 | Feb 26, 2025 |
| Ubuntu | — | Upgrade linux-azureUpgrade linux-gkeUpgrade linux-aws-5.15Upgrade linux-lowlatency-hwe-5.15Upgrade linux-oracle-5.15Upgrade linux-azure-fde-5.15Upgrade linux-aws-hweUpgrade linux-hwe-5.15Upgrade linux-aws-5.4Upgrade linux-raspiUpgrade linux-nvidiaUpgrade linux-intel-iotg-5.15Upgrade linux-azure-5.15Upgrade linux-oracle-5.4Upgrade linux-azure-fipsUpgrade linux-gkeopUpgrade linux-oracleUpgrade linux-iotUpgrade linuxUpgrade linux-gcp-5.15Upgrade linux-lowlatencyUpgrade linux-realtimeUpgrade linux-fipsUpgrade linux-gcp-fipsUpgrade linux-intel-iotgUpgrade linux-hweUpgrade linux-azure-5.4Upgrade linux-hwe-5.4Upgrade linux-aws-fipsUpgrade linux-bluefieldUpgrade linux-riscv-5.15Upgrade linux-azure-4.15Upgrade linux-gcp-4.15Upgrade linux-ibm-5.4Upgrade linux-ibmUpgrade linux-raspi-5.4Upgrade linux-kvmUpgrade linux-awsUpgrade linux-gcpUpgrade linux-gcp-5.4 | Mar 3, 2025 | Feb 26, 2025 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | May 27, 2026 | Feb 26, 2025 |
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