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.
Product status
dee1f973ca341c266229faa5a1a5bb268bed3531 (git) before 58ddae5d77b1db3a27b891c75a8fa120239ac092
dee1f973ca341c266229faa5a1a5bb268bed3531 (git) before d17857b4fb9ba5745b59be0ef38fd532991fccbf
dee1f973ca341c266229faa5a1a5bb268bed3531 (git) before d67c8ecf3d8fda9b8ef80e6f665d84b6d6ac9d88
dee1f973ca341c266229faa5a1a5bb268bed3531 (git) before 7015fcf473796e1d2d876f241bd9e0c36f3d4eef
dee1f973ca341c266229faa5a1a5bb268bed3531 (git) before 1bf6974822d1dba86cf11b5f05498581cf3488a2
814a7833df19e1de7447f870ae890adb12561627 (git)
4319fd00002630a761fa5559a086f11ed7623006 (git)
e28b27be06c5e6a5236c0c0b370ca0768ab086bb (git)
3.2.33 (semver) before 3.3
3.4.16 (semver) before 3.5
3.6.4 (semver) before 3.7
3.7
Any version before 3.7
6.6.130 (semver)
6.12.75 (semver)
6.18.14 (semver)
6.19.4 (semver)
7.0 (original_commit_for_fix)
References
git.kernel.org/...c/58ddae5d77b1db3a27b891c75a8fa120239ac092
git.kernel.org/...c/d17857b4fb9ba5745b59be0ef38fd532991fccbf
git.kernel.org/...c/d67c8ecf3d8fda9b8ef80e6f665d84b6d6ac9d88
git.kernel.org/...c/7015fcf473796e1d2d876f241bd9e0c36f3d4eef
git.kernel.org/...c/1bf6974822d1dba86cf11b5f05498581cf3488a2