CVE-2024-35807 — linux / linux_kernel
In the Linux kernel, the following vulnerability has been resolved:
ext4: fix corruption during on-line resize
We observed a corruption during on-line resize of a file system that is larger than 16 TiB with 4k block size. With having more then 2^32 blocks resize_inode is turned off by default by mke2fs. The issue can be reproduced on a smaller file system for convenience by explicitly turning off resize_inode. An on-line resize across an 8 GiB boundary (the size of a meta block group in this setup) then leads to a corruption:
dev=/dev/<some_dev> # should be >= 16 GiB mkdir -p /corruption /sbin/mke2fs -t ext4 -b 4096 -O ^resize_inode $dev $((2 * 221 - 215)) mount -t ext4 $dev /corruption
dd if=/dev/zero bs=4096 of=/corruption/test count=$((22**21 - 42**15)) sha1sum /corruption/test
79d2658b39dcfd77274e435b0934028adafaab11 /corruption/test
/sbin/resize2fs $dev $((2*2**21))
drop page cache to force reload the block from disk
echo 1 > /proc/sys/vm/drop_caches
sha1sum /corruption/test
3c2abc63cbf1a94c9e6977e0fbd72cd832c4d5c3 /corruption/test
2^21 = 2^15*2^6 equals 8 GiB whereof 2^15 is the number of blocks per block group and 2^6 are the number of block groups that make a meta block group.
The last checksum might be different depending on how the file is laid out across the physical blocks. The actual corruption occurs at physical block 63*2^15 = 2064384 which would be the location of the backup of the meta block group's block descriptor. During the on-line resize the file system will be converted to meta_bg starting at s_first_meta_bg which is 2 in the example - meaning all block groups after 16 GiB. However, in ext4_flex_group_add we might add block groups that are not part of the first meta block group yet. In the reproducer we achieved this by substracting the size of a whole block group from the point where the meta block group would start. This must be considered when updating the backup block group descriptors to follow the non-meta_bg layout. The fix is to add a test whether the group to add is already part of the meta block group or not.
| Software | From | Fixed in |
|---|---|---|
| linux / linux_kernel | 3.7 | 4.19.312 |
| linux / linux_kernel | 4.20 | 5.4.274 |
| linux / linux_kernel | 5.5 | 5.10.215 |
| linux / linux_kernel | 5.11 | 5.15.154 |
| linux / linux_kernel | 5.16 | 6.1.84 |
| linux / linux_kernel | 6.2 | 6.6.24 |
| linux / linux_kernel | 6.7 | 6.7.12 |
| linux / linux_kernel | 6.8 | 6.8.3 |
| debian / debian_linux | 10.0 | 10.0.x |
- https://cert-portal.siemens.com/productcert/html/ssa-265688.html
- https://cert-portal.siemens.com/productcert/html/ssa-398330.html
- https://git.kernel.org/stable/c/239c669edb2bffa1aa2612519b1d438ab35d6be6
- https://git.kernel.org/stable/c/37b6a3ba793bbbae057f5b991970ebcc52cb3db5
- https://git.kernel.org/stable/c/722d2c01b8b108f8283d1b7222209d5b2a5aa7bd
- https://git.kernel.org/stable/c/75cc31c2e7193b69f5d25650bda5bb42ed92f8a1
- https://git.kernel.org/stable/c/a6b3bfe176e8a5b05ec4447404e412c2a3fc92cc
- https://git.kernel.org/stable/c/b461910af8ba3bed80f48c2bf852686d05c6fc5c
- https://git.kernel.org/stable/c/e8e8b197317228b5089ed9e7802dadf3ccaa027a
- https://git.kernel.org/stable/c/ee4e9c1976147a850f6085a13fca95bcaa00d84c
- https://git.kernel.org/stable/c/fb1088d51bbaa0faec5a55d4f5818a9ab79e24df
- https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html
- https://lists.debian.org/debian-lts-announce/2024/06/msg00020.html
Deep Security Visibility Without the Complexity
SynScan provides clear, real-time security insights so you can monitor your attack surface, spot risks early, and act fast—without extra complexity.
- No setup fees
- 5-min deployment
- Cancel anytime
Frequently Asked Questions
A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.
CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.
A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.
Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.
Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.
SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.