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CVE PROGRAM SOURCE RECORDUnscored

CVE-2026-45892

ext4: drop extent cache after doing PARTIAL_VALID1 zeroout

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Status
Published
Published
Updated
Assigning organization
Linux

Description

In the Linux kernel, the following vulnerability has been resolved: ext4: drop extent cache after doing PARTIAL_VALID1 zeroout When splitting an unwritten extent in the middle and converting it to initialized in ext4_split_extent() with the EXT4_EXT_MAY_ZEROOUT and EXT4_EXT_DATA_VALID2 flags set, it could leave a stale unwritten extent. Assume we have an unwritten file and buffered write in the middle of it without dioread_nolock enabled, it will allocate blocks as written extent. 0 A B N [UUUUUUUUUUUU] on-disk extent U: unwritten extent [UUUUUUUUUUUU] extent status tree [--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_PARTIAL_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 leave the entire extent as unwritten. 0 A B N [UUUUUUUUUUUU] on-disk extent [UUUUUUUUUUUU] extent status tree [--DDDDDDDDZZ] Z: zeroed 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 leave an written extent from A to N. 0 A B N [UUWWWWWWWWWW] on-disk extent W: written extent [UUUUUUUUUUUU] extent status tree [--DDDDDDDDZZ] Finally ext4_map_create_blocks() only insert extent A to B to the extent status tree, and leave an stale unwritten extent in the status tree. 0 A B N [UUWWWWWWWWWW] on-disk extent W: written extent [UUWWWWWWWWUU] extent status tree [--DDDDDDDDZZ] Fix this issue by always cached extent status entry after zeroing out the second part.

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

  • ddf854e59166533b0f46ba32cd6cd9aca3197d1b to < 28db4bfc6f82fd20e2aadb7fc162244109a4eb31affected
  • 58ddae5d77b1db3a27b891c75a8fa120239ac092 to < f0931a5c17005a0c4fc35bd1a001245effc3354baffected
  • d17857b4fb9ba5745b59be0ef38fd532991fccbf to < d8ee559fccdef713f058cfe5f2c03dc9b18be3b1affected
  • d67c8ecf3d8fda9b8ef80e6f665d84b6d6ac9d88 to < c2ee51d684adca7645e4aa74adca13f6750390bcaffected
  • 7015fcf473796e1d2d876f241bd9e0c36f3d4eef to < a1b962a821e7a52d48212ae269b45808b4411267affected
  • 1bf6974822d1dba86cf11b5f05498581cf3488a2 to < 6d882ea3b0931b43530d44149b79fcd4ffc13030affected

Linux Linux

Default version status: unaffected

  • 6.1.167 to < 6.1.168affected

References