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CVE Record

CVE-2025-40025: f2fs: fix to do sanity check on node footer for non inode dnode

In the Linux kernel, the following vulnerability has been resolved: f2fs: fix to do sanity check on node footer for non inode dnode As syzbot reported below: ------------[ cut here ]------------ kernel BUG at fs/f2fs/file.c:1243! Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI CPU: 0 UID: 0 PID: 5354 Comm: syz.0.0 Not tainted 6.17.0-rc1-syzkaller-00211-g90d970cade8e #0 PREEMPT(full) RIP: 0010:f2fs_truncate_hole+0x69e/0x6c0 fs/f2fs/file.c:1243 Call Trace: <TASK> f2fs_punch_hole+0x2db/0x330 fs/f2fs/file.c:1306 f2fs_fallocate+0x546/0x990 fs/f2fs/file.c:2018 vfs_fallocate+0x666/0x7e0 fs/open.c:342 ksys_fallocate fs/open.c:366 [inline] __do_sys_fallocate fs/open.c:371 [inline] __se_sys_fallocate fs/open.c:369 [inline] __x64_sys_fallocate+0xc0/0x110 fs/open.c:369 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f1e65f8ebe9 w/ a fuzzed image, f2fs may encounter panic due to it detects inconsistent truncation range in direct node in f2fs_truncate_hole(). The root cause is: a non-inode dnode may has the same footer.ino and footer.nid, so the dnode will be parsed as an inode, then ADDRS_PER_PAGE() may return wrong blkaddr count which may be 923 typically, by chance, dn.ofs_in_node is equal to 923, then count can be calculated to 0 in below statement, later it will trigger panic w/ f2fs_bug_on(, count == 0 || ...). count = min(end_offset - dn.ofs_in_node, pg_end - pg_start); This patch introduces a new node_type NODE_TYPE_NON_INODE, then allowing passing the new_type to sanity_check_node_footer in f2fs_get_node_folio() to detect corruption that a non-inode dnode has the same footer.ino and footer.nid. Scripts to reproduce: mkfs.f2fs -f /dev/vdb mount /dev/vdb /mnt/f2fs touch /mnt/f2fs/foo touch /mnt/f2fs/bar dd if=/dev/zero of=/mnt/f2fs/foo bs=1M count=8 umount /mnt/f2fs inject.f2fs --node --mb i_nid --nid 4 --idx 0 --val 5 /dev/vdb mount /dev/vdb /mnt/f2fs xfs_io /mnt/f2fs/foo -c "fpunch 6984k 4k"

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A corrupted or malicious F2FS filesystem image can confuse Linux kernel metadata handling and trigger a kernel panic during a hole-punch operation. This can crash the affected system. The supplied CVSS score is 7.8, but the demonstrated outcome is denial of service; broader confidentiality or integrity impact is not established by the provided evidence.

Executive priority

Prioritize systems that ingest external filesystem images, use removable F2FS media, or permit less-trusted local users. Patch through supported distribution channels. For systems without F2FS exposure, urgency is lower, but version status should still be documented because a kernel crash can materially affect availability.

Technical view

A non-inode direct node can have matching footer inode and node identifiers, causing F2FS to parse it as an inode. This produces an incorrect address count and may reach an invalid zero-count condition in f2fs_truncate_hole(), triggering a kernel BUG. The fix adds a non-inode node type and strengthens footer validation in f2fs_get_node_folio().

Likely exposure

Exposure is limited to Linux systems using or processing F2FS filesystems, particularly those that may mount corrupted or untrusted images. Local access and interaction with the malformed filesystem are indicated. The supplied affected-version data is ambiguous, so distribution-specific package status should be checked against the referenced stable-kernel fixes.

Exploitation context

The issue was found by syzbot using a fuzzed F2FS image. The provided record is not in KEV and supplies no evidence of active exploitation. It describes a local, low-complexity condition requiring low privileges and no user interaction, but does not demonstrate remote exploitation or reliable impact beyond a kernel panic.

Researcher notes

The supplied CVSS vector rates confidentiality, integrity, and availability impacts as high, although the narrative demonstrates only a panic. Treat broader impact as unconfirmed. Version metadata in the bundle is not sufficiently clear for an exact fixed-version statement; use the two stable-kernel commits as patch-presence anchors and consult downstream vendor guidance.

Mitigation direction

  • Install a vendor kernel release that incorporates the referenced upstream F2FS fix.
  • Check Linux distribution advisories and package changelogs for CVE-2025-40025 coverage.
  • Until updated, restrict mounting or processing of untrusted F2FS filesystem images.
  • Apply normal least-privilege controls around filesystem mounting and image ingestion.

Validation and detection

  • Inventory systems that enable, mount, or process F2FS filesystems.
  • Record running kernel and distribution package versions on exposed systems.
  • Confirm package source or changelogs include either referenced stable-kernel fix.
  • Use an authorized regression environment to confirm malformed metadata is rejected without a kernel panic.
  • Review kernel logs for F2FS corruption reports, BUG messages, or related panics.
Prepared
Confidence
high
Sources
4

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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CVE-2025-40025 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
3Timeline events
0ADP providers
3Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2025-40025Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux98e4da8ca301e062d79ae168c67e56f3c3de3ce4, 98e4da8ca301e062d79ae168c67e56f3c3de3ce4unaffected
LinuxLinux3.8, 0, 6.17.2, 6.18affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.