CVE-2026-64064
In the Linux kernel, the following vulnerability has been resolved:
netfs: Fix netfs_invalidate_folio() to clear dirty bit if all changes gone
If a streaming write is made, this will leave the relevant modified folio
in a not-uptodate, but dirty state with a netfs_folio struct hung off of
folio->private indicating the dirty range. Subsequently truncating the
file such that the dirty data in the folio is removed, but the first part
of the folio theoretically remains will cause the netfs_folio struct to be
discarded... but will leave the dirty flag set.
If the folio is then read via mmap(), netfs_read_folio() will see that the
page is dirty and jump to netfs_read_gaps() to fill in the missing bits.
netfs_read_gaps(), however, expects there to be a netfs_folio struct
present and can oops because truncate removed it.
Fix this by calling folio_cancel_dirty() in netfs_invalidate_folio() in the
event that all the dirty data in the folio is erased (as nfs does).
Also add some tracepoints to log modifications to a dirty page.
This can be reproduced with something like:
dd if=/dev/zero of=/xfstest.test/foo bs=1M count=1
umount /xfstest.test
mount /xfstest.test
xfs_io -c "w 0xbbbf 0xf96c" \
-c "truncate 0xbbbf" \
-c "mmap -r 0xb000 0x11000" \
-c "mr 0xb000 0x11000" \
/xfstest.test/foo
with fscaching disabled (otherwise streaming writes are suppressed) and a
change to netfs_perform_write() to disallow streaming writes if the fd is
open O_RDWR:
if (//(file->f_mode & FMODE_READ) || <--- comment this out
netfs_is_cache_enabled(ctx)) {
It should be reproducible even without this change, but if prevents the
above trivial xfs_io command from reproducing it.
Note that the initial dd is important: the file must start out sufficiently
large that the zero-point logic doesn't just clear the gaps because it
knows there's nothing in the file to read yet. Unmounting and mounting is
needed to clear the pagecache (t
CSIRTS triage
- What
- Multiple kernel vulnerabilities across architectures and driver subsystems including AMD processor microarchitectural flaws and cache isolation issues.
- Who is affected
- NVIDIA BaseOS systems running affected Linux kernel versions.
- Urgency
- Moderate; privilege escalation and DoS vectors present, primarily requiring local access.
- Action
- Apply USN-8664-1 kernel security update for NVIDIA BaseOS.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Low exploitation risk0.12% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 2% of all EPSS-scored CVEs.
Advisory coverage (8)
- unknownUSN-8729-1: Linux kernel vulnerabilitiesubuntu · 2026-09-07
- unknownexploitedUSN-8728-1: Linux kernel (GCP) vulnerabilitiesubuntu · 2026-09-07
- unknownUSN-8664-1: Linux kernel (NVIDIA BaseOS) vulnerabilitiesubuntu · 2026-08-20
- unknownUSN-8663-1: Linux kernel (NVIDIA) vulnerabilitiesubuntu · 2026-08-20
- highUSN-8618-1: Linux kernel vulnerabilitiesubuntu · 2026-07-28
- highUSN-8603-1: Linux kernel (Azure) vulnerabilitiesubuntu · 2026-07-24
- highUSN-8593-1: Linux kernel vulnerabilitiesubuntu · 2026-07-23
- unknownCVE-2026-64064: In the Linux kernel, the following vulnerability has been resolved: netfs: Fix netfs_invalidat…nvd · 2026-07-19
External references
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