CVE-2025-71237
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BaseFortify

Publication date: 2026-02-18

Last updated on: 2026-03-18

Assigner: kernel.org

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]
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Meta Information
Published
2026-02-18
Last Modified
2026-03-18
Generated
2026-05-07
AI Q&A
2026-02-18
EPSS Evaluated
2026-05-05
NVD
CVE-2025-71237
Affected Vendors & Products
Showing 7 associated CPEs
Vendor Product Version / Range
linux linux_kernel From 6.19 (inc) to 6.19.1 (exc)
linux linux_kernel From 5.16 (inc) to 6.1.164 (exc)
linux linux_kernel From 5.11 (inc) to 5.15.201 (exc)
linux linux_kernel From 6.2 (inc) to 6.6.125 (exc)
linux linux_kernel From 6.7 (inc) to 6.12.72 (exc)
linux linux_kernel From 6.13 (inc) to 6.18.11 (exc)
linux linux_kernel From 3.15 (inc) to 5.10.251 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-UNKNOWN
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AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability exists in the Linux kernel's nilfs2 filesystem when processing the FITRIM command. An underflow occurs during the calculation of the number of blocks (nblocks) if the end_block value is too small. Because nblocks is an unsigned 64-bit integer, a negative calculation results in a very large positive number. This causes the block layer function __blkdev_issue_discard() to take an excessively long time processing the discard request, holding a lock (ns_segctor_sem) for a prolonged period.

As a result, other tasks cannot acquire this lock, leading to a system hang. The issue typically arises when the ending block is smaller than about 4KiB, potentially causing discard requests beyond the device size. The fix involves safely ignoring such small ranges by treating them as no-ops, avoiding trimming or errors.


How can this vulnerability impact me? :

This vulnerability can cause the affected Linux system to hang or become unresponsive when the FITRIM command is executed with certain parameters. The system hang occurs because a lock remains held for an extended time, blocking other tasks from proceeding.

Such a hang can disrupt normal operations, potentially leading to downtime or degraded system performance until the issue is resolved or the system is restarted.


How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:

I don't know


How can this vulnerability be detected on my network or system? Can you suggest some commands?

I don't know


What immediate steps should I take to mitigate this vulnerability?

I don't know


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