GHSA-WQ7W-GFPQ-89G4
Vulnerability from github – Published: 2026-01-13 18:31 – Updated: 2026-03-25 12:30In the Linux kernel, the following vulnerability has been resolved:
ntfs: set dummy blocksize to read boot_block when mounting
When mounting, sb->s_blocksize is used to read the boot_block without being defined or validated. Set a dummy blocksize before attempting to read the boot_block.
The issue can be triggered with the following syz reproducer:
mkdirat(0xffffffffffffff9c, &(0x7f0000000080)='./file1\x00', 0x0) r4 = openat$nullb(0xffffffffffffff9c, &(0x7f0000000040), 0x121403, 0x0) ioctl$FS_IOC_SETFLAGS(r4, 0x40081271, &(0x7f0000000980)=0x4000) mount(&(0x7f0000000140)=@nullb, &(0x7f0000000040)='./cgroup\x00', &(0x7f0000000000)='ntfs3\x00', 0x2208004, 0x0) syz_clone(0x88200200, 0x0, 0x0, 0x0, 0x0, 0x0)
Here, the ioctl sets the bdev block size to 16384. During mount, get_tree_bdev_flags() calls sb_set_blocksize(sb, block_size(bdev)), but since block_size(bdev) > PAGE_SIZE, sb_set_blocksize() leaves sb->s_blocksize at zero.
Later, ntfs_init_from_boot() attempts to read the boot_block while sb->s_blocksize is still zero, which triggers the bug.
[almaz.alexandrovich@paragon-software.com: changed comment style, added return value handling]
{
"affected": [],
"aliases": [
"CVE-2025-71067"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-01-13T16:16:06Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nntfs: set dummy blocksize to read boot_block when mounting\n\nWhen mounting, sb-\u003es_blocksize is used to read the boot_block without\nbeing defined or validated. Set a dummy blocksize before attempting to\nread the boot_block.\n\nThe issue can be triggered with the following syz reproducer:\n\n mkdirat(0xffffffffffffff9c, \u0026(0x7f0000000080)=\u0027./file1\\x00\u0027, 0x0)\n r4 = openat$nullb(0xffffffffffffff9c, \u0026(0x7f0000000040), 0x121403, 0x0)\n ioctl$FS_IOC_SETFLAGS(r4, 0x40081271, \u0026(0x7f0000000980)=0x4000)\n mount(\u0026(0x7f0000000140)=@nullb, \u0026(0x7f0000000040)=\u0027./cgroup\\x00\u0027,\n \u0026(0x7f0000000000)=\u0027ntfs3\\x00\u0027, 0x2208004, 0x0)\n syz_clone(0x88200200, 0x0, 0x0, 0x0, 0x0, 0x0)\n\nHere, the ioctl sets the bdev block size to 16384. During mount,\nget_tree_bdev_flags() calls sb_set_blocksize(sb, block_size(bdev)),\nbut since block_size(bdev) \u003e PAGE_SIZE, sb_set_blocksize() leaves\nsb-\u003es_blocksize at zero.\n\nLater, ntfs_init_from_boot() attempts to read the boot_block while\nsb-\u003es_blocksize is still zero, which triggers the bug.\n\n[almaz.alexandrovich@paragon-software.com: changed comment style, added\nreturn value handling]",
"id": "GHSA-wq7w-gfpq-89g4",
"modified": "2026-03-25T12:30:19Z",
"published": "2026-01-13T18:31:05Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-71067"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0c9327c8abf9c8f046e45008bb43d94d8ee5c6c5"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/44a38eb4f7876513db5a1bccde74de9bc4389d43"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4fff9a625da958a33191c8553a03283786f9f417"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b3c151fe8f543f1a0b8b5df16ce5d97afa5ec85a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d1693a7d5a38acf6424235a6070bcf5b186a360d"
}
],
"schema_version": "1.4.0",
"severity": []
}
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