GHSA-4WJJ-FC9C-XHFJ
Vulnerability from github – Published: 2026-09-04 18:31 – Updated: 2026-09-04 18:31In the Linux kernel, the following vulnerability has been resolved:
HID: core: fix OOB read of field->usage in hid_set_field()
hid_set_field() hands field->usage + offset to hid_dump_input() before the guard that bounds offset:
hid_dump_input(field->report->device, field->usage + offset, value);
if (offset >= field->report_count) {
hid_err(...);
return -1;
}
Under CONFIG_DEBUG_FS hid_dump_input() dereferences that pointer, with buf = hid_resolv_usage(usage->hid, NULL). The usage[] array is allocated inline with the hid_field in hid_register_field() and holds field->maxusage entries, so an offset past it reads off the end of the kvzalloc()ed allocation and into a neighbouring object. Had the guard run first, offset < report_count <= maxusage would already have confined the pointer to the array.
A caller supplies such an offset today. picolcd_fb_send_tile() validates only report->maxfield before issuing hid_set_field(report->field[0], 11 + i, ...) for i = 0..31, so its offsets are fixed at 11..42 and are never checked against the bound field. When the device registers that field with fewer usages, the framebuffer deferred-io work drives the read on every tile. KASAN reports a 4-byte slab-out-of-bounds read in hid_dump_input() below hid_set_field(), and the same boot logs "offset (1) exceeds report_count (1)" from the guard that runs only afterwards.
Move the hid_dump_input() call below the guard. Because field->maxusage >= field->report_count, the guard then establishes that field->usage + offset lies inside the array before it is dereferenced, for every caller and without changing behaviour on the valid path.
Discovered by XBOW, triaged by Baul Lee baul.lee@xbow.com
{
"affected": [],
"aliases": [
"CVE-2026-80781"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-04T16:18:03Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nHID: core: fix OOB read of field-\u003eusage in hid_set_field()\n\nhid_set_field() hands field-\u003eusage + offset to hid_dump_input() before\nthe guard that bounds offset:\n\n\thid_dump_input(field-\u003ereport-\u003edevice, field-\u003eusage + offset, value);\n\n\tif (offset \u003e= field-\u003ereport_count) {\n\t\thid_err(...);\n\t\treturn -1;\n\t}\n\nUnder CONFIG_DEBUG_FS hid_dump_input() dereferences that pointer, with\nbuf = hid_resolv_usage(usage-\u003ehid, NULL). The usage[] array is\nallocated inline with the hid_field in hid_register_field() and holds\nfield-\u003emaxusage entries, so an offset past it reads off the end of the\nkvzalloc()ed allocation and into a neighbouring object. Had the guard\nrun first, offset \u003c report_count \u003c= maxusage would already have confined\nthe pointer to the array.\n\nA caller supplies such an offset today. picolcd_fb_send_tile()\nvalidates only report-\u003emaxfield before issuing\nhid_set_field(report-\u003efield[0], 11 + i, ...) for i = 0..31, so its\noffsets are fixed at 11..42 and are never checked against the bound\nfield. When the device registers that field with fewer usages, the\nframebuffer deferred-io work drives the read on every tile. KASAN\nreports a 4-byte slab-out-of-bounds read in hid_dump_input() below\nhid_set_field(), and the same boot logs \"offset (1) exceeds\nreport_count (1)\" from the guard that runs only afterwards.\n\nMove the hid_dump_input() call below the guard. Because\nfield-\u003emaxusage \u003e= field-\u003ereport_count, the guard then establishes that\nfield-\u003eusage + offset lies inside the array before it is dereferenced,\nfor every caller and without changing behaviour on the valid path.\n\nDiscovered by XBOW, triaged by Baul Lee \u003cbaul.lee@xbow.com\u003e",
"id": "GHSA-4wjj-fc9c-xhfj",
"modified": "2026-09-04T18:31:25Z",
"published": "2026-09-04T18:31:25Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-80781"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/313ead1abed945544703b100a12c5a10fdf78409"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/465544b3d6602cfbdc2305d5cbfb7f4954353b63"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4993e1ab85d7d3f4a40d81852170f9665483bbd8"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5215ea00a747eca34cb2f603cfef91fef76c2558"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9a1d7c5f0d82e8665715d5e47c9410c6a97e3748"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a13cdb19fcb223ed41bdab3bab42b98dba87e90b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a38212687519f2a72f43e62dec1348a690412404"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c1d9c16af51cc6ff92a5a062617d3b022dd01078"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/cbcc0e8dea499e5ca86b583372ccb1815cccc570"
}
],
"schema_version": "1.4.0",
"severity": []
}
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