ext4: handle wraparound when searching for blocks for indirect mapped blocks
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 5.16, 6.1.168, 6.6.134, 6.12.80, 6.18.21, and 1 more
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: yes
- Technical impact: total
Summary
In the Linux kernel, the following vulnerability has been resolved: ext4: handle wraparound when searching for blocks for indirect mapped blocks Commit 4865c768b563 ("ext4: always allocate blocks only from groups inode can use") restricts what blocks will be allocated for indirect block based files to block numbers that fit within 32-bit block numbers. However, when using a review bot running on the latest Gemini LLM to check this commit when backporting into an LTS based kernel, it raised this concern: If ac->ac_g_ex.fe_group is >= ngroups (for instance, if the goal group was populated via stream allocation from s_mb_last_groups), then start will be >= ngroups. Does this allow allocating blocks beyond the 32-bit limit for indirect block mapped files? The commit message mentions that ext4_mb_scan_groups_linear() takes care to not select unsupported groups. However, its loop uses group = *start, and the very first iteration will call ext4_mb_scan_group() with this unsupported group because next_linear_group() is only called at the end of the iteration. After reviewing the code paths involved and considering the LLM review, I determined that this can happen when there is a file system where some files/directories are extent-mapped and others are indirect-block mapped. To address this, add a safety clamp in ext4_mb_scan_groups().
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: none · Automatable: yes · Technical impact: total
- Record last updated
Affected versions
- Linux Linux
From 9d89b9d55e25cb340c5b4b769876edc551b7a9ff · fixed in f89bba144938921a2249237ad04a0183ff3f8930; From 1b0edd6022a3f44ce87fea9959a9310f4628fbea · fixed in 83170a05908b6cf2fb3235d3065bf613ff866f3c; From 9eea2f57d11b30049ff996ac3eff6e0dc8089e5f · fixed in 4bec4a498ce86314d470ae6144120461f2138c29; From 34c803edc0b3365a42efcf9815acab63b4cf54e0 · fixed in 12624c5b724a81e14e532972b40d863b0de3b7d1; From 321ed8d559c951e71ad2d2d69a4cf0445644e865 · fixed in 2a368ccddfc492a0aa951e2caef2985f20e96503; From 4865c768b563deff1b6a6384e74a62f143427b42 · fixed in bb81702370fad22c06ca12b6e1648754dbc37e0f; From 5.15.203 · fixed in 5.16
- Linux Linux
From 6.1.167 · fixed in 6.1.168; From 6.6.130 · fixed in 6.6.134; From 6.12.77 · fixed in 6.12.80; From 6.18.14 · fixed in 6.18.21; From 6.19.4 · fixed in 6.19.11
- KernelLinux
From 6.1.167 · fixed in 6.1.168; From 6.6.130 · fixed in 6.6.134; From 6.12.77 · fixed in 6.12.80; From 6.18.14 · fixed in 6.18.21; From 6.19.4 · fixed in 6.19.11