GHSA-37G9-2P78-FR5W
Vulnerability from github – Published: 2026-08-15 06:32 – Updated: 2026-08-17 06:33In the Linux kernel, the following vulnerability has been resolved:
minix: avoid overflow in bitmap block count calculation
minix_check_superblock() uses minix_blocks_needed() to verify that the on-disk imap and zmap block counts are large enough for the advertised inode and zone counts.
The helper currently performs DIV_ROUND_UP() in unsigned int arithmetic. A Minix v3 image can set s_ninodes or s_zones near UINT_MAX so the addition inside DIV_ROUND_UP() wraps to zero. That makes a zero imap/zmap block count look valid, after which minix_fill_super() can dereference s_imap[0] or s_zmap[0] even though no bitmap buffers were allocated.
Impact: mounting a crafted Minix v3 image whose s_ninodes or s_zones is near UINT_MAX makes minix_check_superblock() accept a zero bitmap-block count and minix_fill_super() dereference s_imap[0]/s_zmap[0], panicking the kernel.
The divisor is the bitmap capacity in bits, blocksize * 8, which is always a power of two: minix_fill_super() obtains the block size through sb_set_blocksize(), and blk_validate_block_size() rejects any size that is not a power of two. Use DIV_ROUND_UP_POW2(), which divides before adding the round-up term and so cannot overflow for a power-of-two divisor.
{
"affected": [],
"aliases": [
"CVE-2026-72369"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-15T06:22:10Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nminix: avoid overflow in bitmap block count calculation\n\nminix_check_superblock() uses minix_blocks_needed() to verify that the\non-disk imap and zmap block counts are large enough for the advertised\ninode and zone counts.\n\nThe helper currently performs DIV_ROUND_UP() in unsigned int arithmetic.\nA Minix v3 image can set s_ninodes or s_zones near UINT_MAX so the\naddition inside DIV_ROUND_UP() wraps to zero. That makes a zero imap/zmap\nblock count look valid, after which minix_fill_super() can dereference\ns_imap[0] or s_zmap[0] even though no bitmap buffers were allocated.\n\nImpact: mounting a crafted Minix v3 image whose s_ninodes or s_zones is\nnear UINT_MAX makes minix_check_superblock() accept a zero bitmap-block\ncount and minix_fill_super() dereference s_imap[0]/s_zmap[0], panicking\nthe kernel.\n\nThe divisor is the bitmap capacity in bits, blocksize * 8, which is\nalways a power of two: minix_fill_super() obtains the block size through\nsb_set_blocksize(), and blk_validate_block_size() rejects any size that\nis not a power of two. Use DIV_ROUND_UP_POW2(), which divides before\nadding the round-up term and so cannot overflow for a power-of-two\ndivisor.",
"id": "GHSA-37g9-2p78-fr5w",
"modified": "2026-08-17T06:33:25Z",
"published": "2026-08-15T06:32:21Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-72369"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/8a29e60e2176b02e04f8737c8b32b696230eb0c5"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/959c95340a9e19cd333b4c18935fdeecbb2f319d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a11ebaab50d27d6c4c78506f84ff36452e0b901d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/abe3536a4bedcc43de80b6d4d7e3d57e9ba382a5"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/fb3e566cafc38fe3ba35e6843a2d529a3748870c"
}
],
"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"
}
]
}
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