Description
In the Linux kernel, the following vulnerability has been resolved:

smb/client: invalidate fscache for fallocate range operations

smb3_zero_range(), smb3_punch_hole(), smb3_insert_range(), and
smb3_collapse_range() modify file contents through server-side range
operations. These operations discard the affected page cache, but leave
the FS-Cache cookie valid, so a later read may return data cached before
the range operation.

Fix this by invalidating FS-Cache after outstanding I/O has completed
and before modifying the file on the server.

Run the following as root on a CIFS mount with fsc enabled and an active
CacheFiles backend:

bash -c '
MNT=/mnt/cifs
FILE="$MNT/repro"

# Generate four 1 MiB random blocks: [A][B][C][D].
dd if=/dev/urandom of=/tmp/src bs=1M count=4 status=none

# Expected contents after zeroing B: [A][zero][C][D].
cp /tmp/src /tmp/expected
dd if=/dev/zero of=/tmp/expected bs=1M seek=1 count=1 \
conv=notrunc status=none
cp /tmp/src "$FILE"

# Populate FS-Cache, then discard the page cache.
sync
echo 1 > /proc/sys/vm/drop_caches
cat "$FILE" > /dev/null
sync
echo 1 > /proc/sys/vm/drop_caches

fallocate --zero-range -o 1M -l 1M "$FILE"

if cmp -s /tmp/expected "$FILE"; then
echo "readback: OK"
else
echo "readback: STALE DATA"
fi
'

Before this change, the readback differs from /tmp/expected:

readback: STALE DATA

After this change, it matches:

readback: OK
Published: 2026-09-25
Score: n/a
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
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Remediation

No vendor fix or workaround currently provided.

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History

Fri, 25 Sep 2026 12:45:00 +0000

Type Values Removed Values Added
Weaknesses CWE-203

Fri, 25 Sep 2026 10:45:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: smb/client: invalidate fscache for fallocate range operations smb3_zero_range(), smb3_punch_hole(), smb3_insert_range(), and smb3_collapse_range() modify file contents through server-side range operations. These operations discard the affected page cache, but leave the FS-Cache cookie valid, so a later read may return data cached before the range operation. Fix this by invalidating FS-Cache after outstanding I/O has completed and before modifying the file on the server. Run the following as root on a CIFS mount with fsc enabled and an active CacheFiles backend: bash -c ' MNT=/mnt/cifs FILE="$MNT/repro" # Generate four 1 MiB random blocks: [A][B][C][D]. dd if=/dev/urandom of=/tmp/src bs=1M count=4 status=none # Expected contents after zeroing B: [A][zero][C][D]. cp /tmp/src /tmp/expected dd if=/dev/zero of=/tmp/expected bs=1M seek=1 count=1 \ conv=notrunc status=none cp /tmp/src "$FILE" # Populate FS-Cache, then discard the page cache. sync echo 1 > /proc/sys/vm/drop_caches cat "$FILE" > /dev/null sync echo 1 > /proc/sys/vm/drop_caches fallocate --zero-range -o 1M -l 1M "$FILE" if cmp -s /tmp/expected "$FILE"; then echo "readback: OK" else echo "readback: STALE DATA" fi ' Before this change, the readback differs from /tmp/expected: readback: STALE DATA After this change, it matches: readback: OK
Title smb/client: invalidate fscache for fallocate range operations
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-09-25T10:36:06.581Z

Reserved: 2026-09-25T10:25:14.318Z

Link: CVE-2026-98124

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-25T11:17:43.720

Modified: 2026-09-25T11:17:43.720

Link: CVE-2026-98124

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-25T12:30:08Z

Weaknesses