ghsa-6g66-96c8-x7cw
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
nilfs2: do not force clear folio if buffer is referenced
Patch series "nilfs2: protect busy buffer heads from being force-cleared".
This series fixes the buffer head state inconsistency issues reported by syzbot that occurs when the filesystem is corrupted and falls back to read-only, and the associated buffer head use-after-free issue.
This patch (of 2):
Syzbot has reported that after nilfs2 detects filesystem corruption and falls back to read-only, inconsistencies in the buffer state may occur.
One of the inconsistencies is that when nilfs2 calls mark_buffer_dirty() to set a data or metadata buffer as dirty, but it detects that the buffer is not in the uptodate state:
WARNING: CPU: 0 PID: 6049 at fs/buffer.c:1177 mark_buffer_dirty+0x2e5/0x520 fs/buffer.c:1177 ... Call Trace: nilfs_palloc_commit_alloc_entry+0x4b/0x160 fs/nilfs2/alloc.c:598 nilfs_ifile_create_inode+0x1dd/0x3a0 fs/nilfs2/ifile.c:73 nilfs_new_inode+0x254/0x830 fs/nilfs2/inode.c:344 nilfs_mkdir+0x10d/0x340 fs/nilfs2/namei.c:218 vfs_mkdir+0x2f9/0x4f0 fs/namei.c:4257 do_mkdirat+0x264/0x3a0 fs/namei.c:4280 __do_sys_mkdirat fs/namei.c:4295 [inline] __se_sys_mkdirat fs/namei.c:4293 [inline] __x64_sys_mkdirat+0x87/0xa0 fs/namei.c:4293 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f
The other is when nilfs_btree_propagate(), which propagates the dirty state to the ancestor nodes of a b-tree that point to a dirty buffer, detects that the origin buffer is not dirty, even though it should be:
WARNING: CPU: 0 PID: 5245 at fs/nilfs2/btree.c:2089 nilfs_btree_propagate+0xc79/0xdf0 fs/nilfs2/btree.c:2089 ... Call Trace: nilfs_bmap_propagate+0x75/0x120 fs/nilfs2/bmap.c:345 nilfs_collect_file_data+0x4d/0xd0 fs/nilfs2/segment.c:587 nilfs_segctor_apply_buffers+0x184/0x340 fs/nilfs2/segment.c:1006 nilfs_segctor_scan_file+0x28c/0xa50 fs/nilfs2/segment.c:1045 nilfs_segctor_collect_blocks fs/nilfs2/segment.c:1216 [inline] nilfs_segctor_collect fs/nilfs2/segment.c:1540 [inline] nilfs_segctor_do_construct+0x1c28/0x6b90 fs/nilfs2/segment.c:2115 nilfs_segctor_construct+0x181/0x6b0 fs/nilfs2/segment.c:2479 nilfs_segctor_thread_construct fs/nilfs2/segment.c:2587 [inline] nilfs_segctor_thread+0x69e/0xe80 fs/nilfs2/segment.c:2701 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
Both of these issues are caused by the callbacks that handle the page/folio write requests, forcibly clear various states, including the working state of the buffers they hold, at unexpected times when they detect read-only fallback.
Fix these issues by checking if the buffer is referenced before clearing the page/folio state, and skipping the clear if it is.
{
"affected": [],
"aliases": [
"CVE-2025-21722"
],
"database_specific": {
"cwe_ids": [
"CWE-416"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-02-27T02:15:15Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnilfs2: do not force clear folio if buffer is referenced\n\nPatch series \"nilfs2: protect busy buffer heads from being force-cleared\".\n\nThis series fixes the buffer head state inconsistency issues reported by\nsyzbot that occurs when the filesystem is corrupted and falls back to\nread-only, and the associated buffer head use-after-free issue.\n\n\nThis patch (of 2):\n\nSyzbot has reported that after nilfs2 detects filesystem corruption and\nfalls back to read-only, inconsistencies in the buffer state may occur.\n\nOne of the inconsistencies is that when nilfs2 calls mark_buffer_dirty()\nto set a data or metadata buffer as dirty, but it detects that the buffer\nis not in the uptodate state:\n\n WARNING: CPU: 0 PID: 6049 at fs/buffer.c:1177 mark_buffer_dirty+0x2e5/0x520\n fs/buffer.c:1177\n ...\n Call Trace:\n \u003cTASK\u003e\n nilfs_palloc_commit_alloc_entry+0x4b/0x160 fs/nilfs2/alloc.c:598\n nilfs_ifile_create_inode+0x1dd/0x3a0 fs/nilfs2/ifile.c:73\n nilfs_new_inode+0x254/0x830 fs/nilfs2/inode.c:344\n nilfs_mkdir+0x10d/0x340 fs/nilfs2/namei.c:218\n vfs_mkdir+0x2f9/0x4f0 fs/namei.c:4257\n do_mkdirat+0x264/0x3a0 fs/namei.c:4280\n __do_sys_mkdirat fs/namei.c:4295 [inline]\n __se_sys_mkdirat fs/namei.c:4293 [inline]\n __x64_sys_mkdirat+0x87/0xa0 fs/namei.c:4293\n do_syscall_x64 arch/x86/entry/common.c:52 [inline]\n do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nThe other is when nilfs_btree_propagate(), which propagates the dirty\nstate to the ancestor nodes of a b-tree that point to a dirty buffer,\ndetects that the origin buffer is not dirty, even though it should be:\n\n WARNING: CPU: 0 PID: 5245 at fs/nilfs2/btree.c:2089\n nilfs_btree_propagate+0xc79/0xdf0 fs/nilfs2/btree.c:2089\n ...\n Call Trace:\n \u003cTASK\u003e\n nilfs_bmap_propagate+0x75/0x120 fs/nilfs2/bmap.c:345\n nilfs_collect_file_data+0x4d/0xd0 fs/nilfs2/segment.c:587\n nilfs_segctor_apply_buffers+0x184/0x340 fs/nilfs2/segment.c:1006\n nilfs_segctor_scan_file+0x28c/0xa50 fs/nilfs2/segment.c:1045\n nilfs_segctor_collect_blocks fs/nilfs2/segment.c:1216 [inline]\n nilfs_segctor_collect fs/nilfs2/segment.c:1540 [inline]\n nilfs_segctor_do_construct+0x1c28/0x6b90 fs/nilfs2/segment.c:2115\n nilfs_segctor_construct+0x181/0x6b0 fs/nilfs2/segment.c:2479\n nilfs_segctor_thread_construct fs/nilfs2/segment.c:2587 [inline]\n nilfs_segctor_thread+0x69e/0xe80 fs/nilfs2/segment.c:2701\n kthread+0x2f0/0x390 kernel/kthread.c:389\n ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147\n ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244\n \u003c/TASK\u003e\n\nBoth of these issues are caused by the callbacks that handle the\npage/folio write requests, forcibly clear various states, including the\nworking state of the buffers they hold, at unexpected times when they\ndetect read-only fallback.\n\nFix these issues by checking if the buffer is referenced before clearing\nthe page/folio state, and skipping the clear if it is.",
"id": "GHSA-6g66-96c8-x7cw",
"modified": "2025-03-13T15:32:48Z",
"published": "2025-02-27T03:34:02Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-21722"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1098bb8d52419d262a3358d099a1598a920b730f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/19296737024cd220a1d6590bf4c092bca8c99497"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4d042811c72f71be7c14726db2c72b67025a7cb5"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/557ccf5e49f1fb848a29698585bcab2e50a597ef"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7d0544bacc11d6aa26ecd7debf9353193c7a3328"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ca76bb226bf47ff04c782cacbd299f12ddee1ec1"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f51ff43c4c5a6c8e72d0aca89e4d5e688938412f"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
Sightings
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