CVE-2026-45858ext4: don't zero the entire extent if EXT4_EXT_DATA_PARTIAL_VALID1
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In the Linux kernel, the following vulnerability has been resolved: ext4: don't zero the entire extent if EXT4_EXT_DATA_PARTIAL_VALID1 When allocating initialized blocks from a large unwritten extent, or when splitting an unwritten extent during end I/O and converting it to initialized, there is currently a potential issue of stale data if the extent needs to be split in the middle. 0 A B N [UUUUUUUUUUUU] U: unwritten extent [--DDDDDDDD--] D: valid data |<- ->| ----> this range needs to be initialized ext4_split_extent() first try to split this extent at B with EXT4_EXT_DATA_ENTIRE_VALID1 and EXT4_EXT_MAY_ZEROOUT flag set, but ext4_split_extent_at() failed to split this extent due to temporary lack of space. It zeroout B to N and mark the entire extent from 0 to N as written. 0 A B N [WWWWWWWWWWWW] W: written extent [SSDDDDDDDDZZ] Z: zeroed, S: stale data ext4_split_extent() then try to split this extent at A with EXT4_EXT_DATA_VALID2 flag set. This time, it split successfully and left a stale written extent from 0 to A. 0 A B N [WW|WWWWWWWWWW] [SS|DDDDDDDDZZ] Fix this by pass EXT4_EXT_DATA_PARTIAL_VALID1 to ext4_split_extent_at() when splitting at B, don't convert the entire extent to written and left it as unwritten after zeroing out B to N. The remaining work is just like the standard two-part split. ext4_split_extent() will pass the EXT4_EXT_DATA_VALID2 flag when it calls ext4_split_extent_at() for the second time, allowing it to properly handle the split. If the split is successful, it will keep extent from 0 to A as unwritten.
- CVSS
- 5.5 MEDIUM (v3.1, NVD)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Analyzed
- Record last updated
- May 30, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from dee1f973ca341c266229faa5a1a5bb268bed3531 before 58ddae5d77b1db3a27b891c75a8fa120239ac092; from dee1f973ca341c266229faa5a1a5bb268bed3531 before d17857b4fb9ba5745b59be0ef38fd532991fccbf; from dee1f973ca341c266229faa5a1a5bb268bed3531 before d67c8ecf3d8fda9b8ef80e6f665d84b6d6ac9d88; from dee1f973ca341c266229faa5a1a5bb268bed3531 before 7015fcf473796e1d2d876f241bd9e0c36f3d4eef; from dee1f973ca341c266229faa5a1a5bb268bed3531 before 1bf6974822d1dba86cf11b5f05498581cf3488a2; 814a7833df19e1de7447f870ae890adb12561627; 4319fd00002630a761fa5559a086f11ed7623006; e28b27be06c5e6a5236c0c0b370ca0768ab086bb; and 3 more ranges | CNA record |
linux linux_kernel linux:linux_kernel | from 3.2.33 before 3.3; from 3.4.16 before 3.5; from 3.6.4 before 3.7; from 3.7.1 before 6.6.130; from 6.7 before 6.12.75; from 6.13 before 6.18.14; from 6.19 before 6.19.4; 3.7; and 6 more ranges | NVD |
References
- https://git.kernel.org/stable/c/58ddae5d77b1db3a27b891c75a8fa120239ac092patch
- https://git.kernel.org/stable/c/d17857b4fb9ba5745b59be0ef38fd532991fccbfpatch
- https://git.kernel.org/stable/c/d67c8ecf3d8fda9b8ef80e6f665d84b6d6ac9d88patch
- https://git.kernel.org/stable/c/7015fcf473796e1d2d876f241bd9e0c36f3d4eefpatch
- https://git.kernel.org/stable/c/1bf6974822d1dba86cf11b5f05498581cf3488a2patch
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.