smb/client: validate new EOF for zero range
When FALLOC_FL_ZERO_RANGE is used without FALLOC_FL_KEEP_SIZE,
smb3_zero_range() may extend EOF without checking RLIMIT_FSIZE, allowing
the file to grow beyond the caller's file-size limit.
Fix this by calling inode_newsize_ok() before sending the zero-range
request when the operation would extend EOF.
Reproducer, using a file on a CIFS mount:
bash -c '
FILE=/mnt/cifs/repro
trap "" SIGXFSZ
ulimit -f 3072
truncate -s 2M "$FILE"
fallocate --zero-range -o 0 -l 4M "$FILE"
echo "fallocate rc=$?"
stat -c "file size=%s" "$FILE"
'
Before this change, the operation succeeds despite the 3 MiB limit:
fallocate rc=0
file size=4194304
After this change, fallocate fails and leaves the file at 2 MiB.
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| Vendors | Products |
|---|---|
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Linux
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Linux Kernel
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Solution
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Workaround
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Fri, 25 Sep 2026 12:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-367 |
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: validate new EOF for zero range When FALLOC_FL_ZERO_RANGE is used without FALLOC_FL_KEEP_SIZE, smb3_zero_range() may extend EOF without checking RLIMIT_FSIZE, allowing the file to grow beyond the caller's file-size limit. Fix this by calling inode_newsize_ok() before sending the zero-range request when the operation would extend EOF. Reproducer, using a file on a CIFS mount: bash -c ' FILE=/mnt/cifs/repro trap "" SIGXFSZ ulimit -f 3072 truncate -s 2M "$FILE" fallocate --zero-range -o 0 -l 4M "$FILE" echo "fallocate rc=$?" stat -c "file size=%s" "$FILE" ' Before this change, the operation succeeds despite the 3 MiB limit: fallocate rc=0 file size=4194304 After this change, fallocate fails and leaves the file at 2 MiB. | |
| Title | smb/client: validate new EOF for zero range | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-09-25T10:36:07.797Z
Reserved: 2026-09-25T10:25:14.318Z
Link: CVE-2026-98126
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-25T11:17:43.940
Modified: 2026-09-25T11:17:43.940
Link: CVE-2026-98126
Redhat
No data.
OpenCVE Enrichment
Updated: 2026-09-25T12:45:16Z