PT-2026-61476 · Linux · Linux

CVE-2026-64159

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Publicado

2026-07-19

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Atualizado

2026-07-19

Nenhuma

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In the Linux kernel, the following vulnerability has been resolved:
netfs: Fix zeropoint update where i size > remote i size
Fix the update of the zero point[*] by netfs release folio() when there is uncommitted data in the pagecache beyond the folio being released but the on-server EOF is in this folio (ie. i size > remote i size). The update needs to limit zero point to remote i size, not i size as i size is a local phenomenon reflecting updates made locally to the pagecache, not stuff written to the server. remote i size tracks the server's i size.
[*] The zero point is the file position from which we can assume that the server will just return zeros, so we can avoid generating reads.
Note that netfs invalidate folio() probably doesn't need fixing as zero point should be updated by setattr after truncation or fallocate.
Found with:
fsx -q -N 1000000 -p 10000 -o 128000 -l 600000 /xfstest.test/junk --replay-ops=junk.fsxops
using the following as junk.fsxops:
truncate 0x0 0x1bbae 0x82864 write 0x3ef2e 0xf9c8 0x1bbae write 0x67e05 0xcb5a 0x4e8f6 mapread 0x57781 0x85b6 0x7495f copy range 0x5d3d 0x10329 0x54fac 0x7495f write 0x64710 0x1c2b 0x7495f mapread 0x64000 0x1000 0x7495f
on cifs with the default cache option.
It shows read-gaps on folio 0x64 failing with a short read (ie. it hits EOF) if the FMODE READ check is commented out in netfs perform write():
    if (//(file->f mode & FMODE READ) ||
      netfs is cache enabled(ctx)) {
and no fscache. This was initially found with the generic/522 xfstest.
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Identificadores relacionados

CVE-2026-64159

Produtos afetados

Linux