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CVE PROGRAM SOURCE RECORDUnscored

CVE-2026-45858

ext4: don't zero the entire extent if EXT4_EXT_DATA_PARTIAL_VALID1

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Status
Published
Published
Updated
Assigning organization
Linux

Description

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.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • dee1f973ca341c266229faa5a1a5bb268bed3531 to < 58ddae5d77b1db3a27b891c75a8fa120239ac092affected
  • dee1f973ca341c266229faa5a1a5bb268bed3531 to < d17857b4fb9ba5745b59be0ef38fd532991fccbfaffected
  • dee1f973ca341c266229faa5a1a5bb268bed3531 to < d67c8ecf3d8fda9b8ef80e6f665d84b6d6ac9d88affected
  • dee1f973ca341c266229faa5a1a5bb268bed3531 to < 7015fcf473796e1d2d876f241bd9e0c36f3d4eefaffected
  • dee1f973ca341c266229faa5a1a5bb268bed3531 to < 1bf6974822d1dba86cf11b5f05498581cf3488a2affected
  • 814a7833df19e1de7447f870ae890adb12561627affected
  • 4319fd00002630a761fa5559a086f11ed7623006affected
  • e28b27be06c5e6a5236c0c0b370ca0768ab086bbaffected
  • 3.2.33 to < 3.3affected
  • 3.4.16 to < 3.5affected
  • 3.6.4 to < 3.7affected

Linux Linux

Default version status: affected

  • 3.7affected
  • 0 to < 3.7unaffected
  • 6.6.130 to ≤ 6.6.*unaffected
  • 6.12.75 to ≤ 6.12.*unaffected
  • 6.18.14 to ≤ 6.18.*unaffected
  • 6.19.4 to ≤ 6.19.*unaffected
  • 7.0 to ≤ *unaffected

References