GHSA-3GFH-MQ5V-C264
Vulnerability from github – Published: 2026-07-19 12:30 – Updated: 2026-07-24 15:32In the Linux kernel, the following vulnerability has been resolved:
NFSv4/flexfiles: reject zero filehandle version count
ff_layout_alloc_lseg() decodes the filehandle-version array count from the flexfiles layout body. The value is used as the count for kzalloc_objs(), and the current code only rejects NULL.
A zero count yields ZERO_SIZE_PTR, which can be stored in dss_info->fh_versions even though later flexfiles paths assume that at least one filehandle version exists.
Reject fh_count == 0 before the allocation, matching the existing zero version_count validation in the flexfiles GETDEVICEINFO parser.
A QEMU/KASAN run with a malformed flexfiles layout hit:
KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017] RIP: 0010:ff_layout_encode_ff_layoutupdate.isra.0+0x15f/0x750 ff_layout_encode_layoutreturn+0x683/0x970 nfs4_xdr_enc_layoutreturn+0x278/0x3a0 Kernel panic - not syncing: Fatal exception
The patched kernel rejects the malformed layout without KASAN/oops/panic, and a valid fh_count=1 regression still opens, reads, and unmounts cleanly.
{
"affected": [],
"aliases": [
"CVE-2026-53392"
],
"database_specific": {
"cwe_ids": [
"CWE-476"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-07-19T12:16:50Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFSv4/flexfiles: reject zero filehandle version count\n\nff_layout_alloc_lseg() decodes the filehandle-version array count\nfrom the flexfiles layout body. The value is used as the count for\nkzalloc_objs(), and the current code only rejects NULL.\n\nA zero count yields ZERO_SIZE_PTR, which can be stored in\ndss_info-\u003efh_versions even though later flexfiles paths assume that at\nleast one filehandle version exists.\n\nReject fh_count == 0 before the allocation, matching the existing zero\nversion_count validation in the flexfiles GETDEVICEINFO parser.\n\nA QEMU/KASAN run with a malformed flexfiles layout hit:\n\n KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]\n RIP: 0010:ff_layout_encode_ff_layoutupdate.isra.0+0x15f/0x750\n ff_layout_encode_layoutreturn+0x683/0x970\n nfs4_xdr_enc_layoutreturn+0x278/0x3a0\n Kernel panic - not syncing: Fatal exception\n\nThe patched kernel rejects the malformed layout without KASAN/oops/panic,\nand a valid fh_count=1 regression still opens, reads, and unmounts cleanly.",
"id": "GHSA-3gfh-mq5v-c264",
"modified": "2026-07-24T15:32:42Z",
"published": "2026-07-19T12:30:22Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-53392"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/18cc6d57a14fa65ab2a2b52279f549041c4bc9cf"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2131ed64b767ffa8bcdb3677d90f3964e39aabc8"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2c6bb3c40bc24f6aa8dfbe6fe98c3ad6389203f2"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7779c85028a0676fb190cde4f0c540f4f8e97761"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9033591535c066726f5b505126ccb4068b98fa4f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/be7829715e341b42846437dd9e721005db59f0cc"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d8c90c7cc061265d5f2813a1f5c82ef2f4707e67"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/eeabb9020721db6bc132e68eeae380b8d4fb4b04"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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