{"id":"CVE-2026-93235","published":"2026-09-24T16:17:19.150","lastModified":"2026-09-25T13:17:17.770","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix to zero post-EOF data when extending file size\n\ngeneric/794  4s ... - output mismatch (see /share/git/fstests/results//generic/794.out.bad)\n    --- tests/generic/794.out   2026-06-12 08:46:32.766426241 +0800\n    +++ /share/git/fstests/results//generic/794.out.bad 2026-07-05 18:32:55.000000000 +0800\n    @@ -1,4 +1,16 @@\n     QA output created by 794\n     append_write\n    +FAIL: non-zero data in gap [4080,4096) after shutdown+remount\n    +000000 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a  >ZZZZZZZZZZZZZZZZ<\n    +*\n    +001000\n     truncate_up\n    ...\n    (Run 'diff -u /share/git/fstests/tests/generic/794.out /share/git/fstests/results//generic/794.out.bad'  to see the entire diff)\nRan: generic/794\nFailures: generic/794\nFailed 1 of 1 tests\n\nSteps of generic/794:\n1. write 4096 bytes to file w/ 0x5a\n2. use fiemap to get PBA of first block in file\n3. truncate file to 4080\n4. umount; write 4096 bytes to file w/ 0x5a directly via PBA; mount\n5. extend filesize via\n   a) append 4096 from offset 4096, or\n   b) truncate 8192, or\n   c) fallocate 4096 from offset 4096\n6. verify the gap is zeroed in memory [4080,4096)\n7. sync range 4096 from offset 4096; shutdown -f (flush meta before shutdown)\n8. umount; mount; verify [4080,4096) is zeroed or not.\n\nWhen extending file size (e.g. via truncate, fallocate, or write) across an\nunaligned EOF boundary, we need to ensure that post-EOF data in the partial\npage is zeroed out in pagecache and marked dirty, then writeback the cache to\npersist zeroed data before committing inode w/ updated i_size.\n\nThis help to prevent stale disk data beyond the previous EOF from being exposed\nafter remounting or crash recovery.\n\nSince f2fs is a LFS filesystem, we only support direct write via PBA in pinfile,\nand pinfile has section-aligned filesize, so in Android, there should no problem,\nbut for other usage in different environment, let's fix this w/ fsync_mode=strict\nmount option.","cvssScore":null,"cvssSeverity":null,"cvssVector":null,"cwes":[],"vendors":[],"products":[],"references":[{"url":"https://git.kernel.org/stable/c/32c7f11a24268ba8d3bb50ea7f54d33f698cd253","tags":[]},{"url":"https://git.kernel.org/stable/c/5eced87b7d19dbc76ebdddaf322046f9ac582fcb","tags":[]},{"url":"https://git.kernel.org/stable/c/6882d458d2e403f6ba7b45542dd31a6b7531eb2e","tags":[]},{"url":"https://git.kernel.org/stable/c/91ec55ddc097ccddd25ffb95a3d079b2ef362372","tags":[]},{"url":"https://git.kernel.org/stable/c/c42608c09b6b5d5967bf211c255914c068c2cde1","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":null}