ghsa-j3rr-hppv-g55q
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
Squashfs: check return result of sb_min_blocksize
Syzkaller reports an "UBSAN: shift-out-of-bounds in squashfs_bio_read" bug.
Syzkaller forks multiple processes which after mounting the Squashfs filesystem, issues an ioctl("/dev/loop0", LOOP_SET_BLOCK_SIZE, 0x8000). Now if this ioctl occurs at the same time another process is in the process of mounting a Squashfs filesystem on /dev/loop0, the failure occurs. When this happens the following code in squashfs_fill_super() fails.
msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE); msblk->devblksize_log2 = ffz(~msblk->devblksize);
sb_min_blocksize() returns 0, which means msblk->devblksize is set to 0.
As a result, ffz(~msblk->devblksize) returns 64, and msblk->devblksize_log2 is set to 64.
This subsequently causes the
UBSAN: shift-out-of-bounds in fs/squashfs/block.c:195:36 shift exponent 64 is too large for 64-bit type 'u64' (aka 'unsigned long long')
This commit adds a check for a 0 return by sb_min_blocksize().
{
"affected": [],
"aliases": [
"CVE-2025-38415"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-07-25T14:15:33Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nSquashfs: check return result of sb_min_blocksize\n\nSyzkaller reports an \"UBSAN: shift-out-of-bounds in squashfs_bio_read\" bug.\n\nSyzkaller forks multiple processes which after mounting the Squashfs\nfilesystem, issues an ioctl(\"/dev/loop0\", LOOP_SET_BLOCK_SIZE, 0x8000). \nNow if this ioctl occurs at the same time another process is in the\nprocess of mounting a Squashfs filesystem on /dev/loop0, the failure\noccurs. When this happens the following code in squashfs_fill_super()\nfails.\n\n----\nmsblk-\u003edevblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE);\nmsblk-\u003edevblksize_log2 = ffz(~msblk-\u003edevblksize);\n----\n\nsb_min_blocksize() returns 0, which means msblk-\u003edevblksize is set to 0.\n\nAs a result, ffz(~msblk-\u003edevblksize) returns 64, and msblk-\u003edevblksize_log2\nis set to 64.\n\nThis subsequently causes the\n\nUBSAN: shift-out-of-bounds in fs/squashfs/block.c:195:36\nshift exponent 64 is too large for 64-bit type \u0027u64\u0027 (aka\n\u0027unsigned long long\u0027)\n\nThis commit adds a check for a 0 return by sb_min_blocksize().",
"id": "GHSA-j3rr-hppv-g55q",
"modified": "2025-07-25T15:30:54Z",
"published": "2025-07-25T15:30:53Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-38415"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0aff95d9bc7fb5400ca8af507429c4b067bdb425"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/295ab18c2dbce8d0ac6ecf7c5187e16e1ac8b282"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4f99357dadbf9c979ad737156ad4c37fadf7c56b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/549f9e3d7b60d53808c98b9fde49b4f46d0524a5"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5c51aa862cbeed2f3887f0382a2708956710bd68"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6abf6b78c6fb112eee495f5636ffcc350dd2ce25"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/734aa85390ea693bb7eaf2240623d41b03705c84"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/db7096ea160e40d78c67fce52e7cc51bde049497"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
| Author | Source | Type | Date |
|---|
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