ghsa-cr67-qf5c-cf5w
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
f2fs: fix to trigger foreground gc during f2fs_map_blocks() in lfs mode
w/ "mode=lfs" mount option, generic/299 will cause system panic as below:
------------[ cut here ]------------ kernel BUG at fs/f2fs/segment.c:2835! Call Trace: f2fs_allocate_data_block+0x6f4/0xc50 f2fs_map_blocks+0x970/0x1550 f2fs_iomap_begin+0xb2/0x1e0 iomap_iter+0x1d6/0x430 __iomap_dio_rw+0x208/0x9a0 f2fs_file_write_iter+0x6b3/0xfa0 aio_write+0x15d/0x2e0 io_submit_one+0x55e/0xab0 __x64_sys_io_submit+0xa5/0x230 do_syscall_64+0x84/0x2f0 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0010:new_curseg+0x70f/0x720
The root cause of we run out-of-space is: in f2fs_map_blocks(), f2fs may trigger foreground gc only if it allocates any physical block, it will be a little bit later when there is multiple threads writing data w/ aio/dio/bufio method in parallel, since we always use OPU in lfs mode, so f2fs_map_blocks() does block allocations aggressively.
In order to fix this issue, let's give a chance to trigger foreground gc in prior to block allocation in f2fs_map_blocks().
{
"affected": [],
"aliases": [
"CVE-2025-38626"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-08-22T16:15:36Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix to trigger foreground gc during f2fs_map_blocks() in lfs mode\n\nw/ \"mode=lfs\" mount option, generic/299 will cause system panic as below:\n\n------------[ cut here ]------------\nkernel BUG at fs/f2fs/segment.c:2835!\nCall Trace:\n \u003cTASK\u003e\n f2fs_allocate_data_block+0x6f4/0xc50\n f2fs_map_blocks+0x970/0x1550\n f2fs_iomap_begin+0xb2/0x1e0\n iomap_iter+0x1d6/0x430\n __iomap_dio_rw+0x208/0x9a0\n f2fs_file_write_iter+0x6b3/0xfa0\n aio_write+0x15d/0x2e0\n io_submit_one+0x55e/0xab0\n __x64_sys_io_submit+0xa5/0x230\n do_syscall_64+0x84/0x2f0\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\nRIP: 0010:new_curseg+0x70f/0x720\n\nThe root cause of we run out-of-space is: in f2fs_map_blocks(), f2fs may\ntrigger foreground gc only if it allocates any physical block, it will be\na little bit later when there is multiple threads writing data w/\naio/dio/bufio method in parallel, since we always use OPU in lfs mode, so\nf2fs_map_blocks() does block allocations aggressively.\n\nIn order to fix this issue, let\u0027s give a chance to trigger foreground\ngc in prior to block allocation in f2fs_map_blocks().",
"id": "GHSA-cr67-qf5c-cf5w",
"modified": "2025-08-22T18:31:22Z",
"published": "2025-08-22T18:31:22Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-38626"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1005a3ca28e90c7a64fa43023f866b960a60f791"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/264ede8a52f18647ed5bb5f2bd9bf54f556ad8f5"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/385e64a0744584397b4b52b27c96703516f39968"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/82765ce5c7a56f9309ee45328e763610eaf11253"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f289690f50a01c3e085d87853392d5b7436a4cee"
}
],
"schema_version": "1.4.0",
"severity": []
}
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