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

nilfs2: Fix potential block overflow that cause system hang

When a user executes the FITRIM command, an underflow can occur when
calculating nblocks if end_block is too small. Since nblocks is of
type sector_t, which is u64, a negative nblocks value will become a
very large positive integer. This ultimately leads to the block layer
function __blkdev_issue_discard() taking an excessively long time to
process the bio chain, and the ns_segctor_sem lock remains held for a
long period. This prevents other tasks from acquiring the ns_segctor_sem
lock, resulting in the hang reported by syzbot in [1].

If the ending block is too small, typically if it is smaller than 4KiB
range, depending on the usage of the segment 0, it may be possible to
attempt a discard request beyond the device size causing the hang.

Exiting successfully and assign the discarded size (0 in this case)
to range->len.

Although the start and len values in the user input range are too small,
a conservative strategy is adopted here to safely ignore them, which is
equivalent to a no-op; it will not perform any trimming and will not
throw an error.

[1]
task:segctord state:D stack:28968 pid:6093 tgid:6093 ppid:2 task_flags:0x200040 flags:0x00080000
Call Trace:
rwbase_write_lock+0x3dd/0x750 kernel/locking/rwbase_rt.c:272
nilfs_transaction_lock+0x253/0x4c0 fs/nilfs2/segment.c:357
nilfs_segctor_thread_construct fs/nilfs2/segment.c:2569 [inline]
nilfs_segctor_thread+0x6ec/0xe00 fs/nilfs2/segment.c:2684

[ryusuke: corrected part of the commit message about the consequences]
Published: 2026-02-18
Score: 5.5 Medium
EPSS: < 1% Very Low
KEV: No
Impact: Denial of Service (system hang)
Action: Apply Patch
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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-4498-1 linux security update
Debian DLA Debian DLA DLA-4499-1 linux-6.1 security update
Debian DSA Debian DSA DSA-6141-1 linux security update
Debian DSA Debian DSA DSA-6163-1 linux security update
History

Mon, 20 Apr 2026 21:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-193

Wed, 18 Mar 2026 15:00:00 +0000

Type Values Removed Values Added
Weaknesses NVD-CWE-noinfo
Metrics cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}


Mon, 23 Feb 2026 03:30:00 +0000


Thu, 19 Feb 2026 16:15:00 +0000


Thu, 19 Feb 2026 00:15:00 +0000


Wed, 18 Feb 2026 15:30:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: nilfs2: Fix potential block overflow that cause system hang When a user executes the FITRIM command, an underflow can occur when calculating nblocks if end_block is too small. Since nblocks is of type sector_t, which is u64, a negative nblocks value will become a very large positive integer. This ultimately leads to the block layer function __blkdev_issue_discard() taking an excessively long time to process the bio chain, and the ns_segctor_sem lock remains held for a long period. This prevents other tasks from acquiring the ns_segctor_sem lock, resulting in the hang reported by syzbot in [1]. If the ending block is too small, typically if it is smaller than 4KiB range, depending on the usage of the segment 0, it may be possible to attempt a discard request beyond the device size causing the hang. Exiting successfully and assign the discarded size (0 in this case) to range->len. Although the start and len values in the user input range are too small, a conservative strategy is adopted here to safely ignore them, which is equivalent to a no-op; it will not perform any trimming and will not throw an error. [1] task:segctord state:D stack:28968 pid:6093 tgid:6093 ppid:2 task_flags:0x200040 flags:0x00080000 Call Trace: rwbase_write_lock+0x3dd/0x750 kernel/locking/rwbase_rt.c:272 nilfs_transaction_lock+0x253/0x4c0 fs/nilfs2/segment.c:357 nilfs_segctor_thread_construct fs/nilfs2/segment.c:2569 [inline] nilfs_segctor_thread+0x6ec/0xe00 fs/nilfs2/segment.c:2684 [ryusuke: corrected part of the commit message about the consequences]
Title nilfs2: Fix potential block overflow that cause system hang
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: 2026-05-11T21:56:59.574Z

Reserved: 2026-02-18T14:25:13.845Z

Link: CVE-2025-71237

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Analyzed

Published: 2026-02-18T16:22:30.517

Modified: 2026-03-18T14:58:45.933

Link: CVE-2025-71237

cve-icon Redhat

Severity :

Publid Date: 2026-02-18T00:00:00Z

Links: CVE-2025-71237 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-04-20T21:00:12Z

Weaknesses