GHSA-M34C-WRF8-MW69
Vulnerability from github – Published: 2026-02-18 18:30 – Updated: 2026-03-18 15:30In 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]
{
"affected": [],
"aliases": [
"CVE-2025-71237"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-02-18T16:22:30Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnilfs2: Fix potential block overflow that cause system hang\n\nWhen a user executes the FITRIM command, an underflow can occur when\ncalculating nblocks if end_block is too small. Since nblocks is of\ntype sector_t, which is u64, a negative nblocks value will become a\nvery large positive integer. This ultimately leads to the block layer\nfunction __blkdev_issue_discard() taking an excessively long time to\nprocess the bio chain, and the ns_segctor_sem lock remains held for a\nlong period. This prevents other tasks from acquiring the ns_segctor_sem\nlock, resulting in the hang reported by syzbot in [1].\n\nIf the ending block is too small, typically if it is smaller than 4KiB\nrange, depending on the usage of the segment 0, it may be possible to\nattempt a discard request beyond the device size causing the hang.\n\nExiting successfully and assign the discarded size (0 in this case)\nto range-\u003elen.\n\nAlthough the start and len values in the user input range are too small,\na conservative strategy is adopted here to safely ignore them, which is\nequivalent to a no-op; it will not perform any trimming and will not\nthrow an error.\n\n[1]\ntask:segctord state:D stack:28968 pid:6093 tgid:6093 ppid:2 task_flags:0x200040 flags:0x00080000\nCall Trace:\n rwbase_write_lock+0x3dd/0x750 kernel/locking/rwbase_rt.c:272\n nilfs_transaction_lock+0x253/0x4c0 fs/nilfs2/segment.c:357\n nilfs_segctor_thread_construct fs/nilfs2/segment.c:2569 [inline]\n nilfs_segctor_thread+0x6ec/0xe00 fs/nilfs2/segment.c:2684\n\n[ryusuke: corrected part of the commit message about the consequences]",
"id": "GHSA-m34c-wrf8-mw69",
"modified": "2026-03-18T15:30:41Z",
"published": "2026-02-18T18:30:40Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-71237"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2438982f635e6cc2009be68ba2efb2998727d8d4"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4aa45f841413cca81882602b4042c53502f34cad"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6457d3ee41a4c15082ac49c5aa7fb933b4a043f3"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b8c5ee234bd54f1447c846101fdaef2cf70c2149"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ba18e5f22f26aa4ef78bc3e81f639d1d4f3845e6"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/df1e20796c9f3d541cca47fb72e4369ea135642d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ea2278657ad0d62596589fbe2caf995e189e65e7"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ed527ef0c264e4bed6c7b2a158ddf516b17f5f66"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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