GHSA-H7P4-FPXW-M265
Vulnerability from github – Published: 2026-04-22 15:31 – Updated: 2026-10-15 03:35In the Linux kernel, the following vulnerability has been resolved:
module: Fix kernel panic when a symbol st_shndx is out of bounds
The module loader doesn't check for bounds of the ELF section index in simplify_symbols():
for (i = 1; i < symsec->sh_size / sizeof(Elf_Sym); i++) {
const char *name = info->strtab + sym[i].st_name;
switch (sym[i].st_shndx) {
case SHN_COMMON:
[...]
default:
/* Divert to percpu allocation if a percpu var. */
if (sym[i].st_shndx == info->index.pcpu)
secbase = (unsigned long)mod_percpu(mod);
else
/** HERE --> **/ secbase = info->sechdrs[sym[i].st_shndx].sh_addr; sym[i].st_value += secbase; break; } }
A symbol with an out-of-bounds st_shndx value, for example 0xffff (known as SHN_XINDEX or SHN_HIRESERVE), may cause a kernel panic:
BUG: unable to handle page fault for address: ... RIP: 0010:simplify_symbols+0x2b2/0x480 ... Kernel panic - not syncing: Fatal exception
This can happen when module ELF is legitimately using SHN_XINDEX or when it is corrupted.
Add a bounds check in simplify_symbols() to validate that st_shndx is within the valid range before using it.
This issue was discovered due to a bug in llvm-objcopy, see relevant discussion for details [1].
[1] https://lore.kernel.org/linux-modules/20251224005752.201911-1-ihor.solodrai@linux.dev/
{
"affected": [],
"aliases": [
"CVE-2026-31521"
],
"database_specific": {
"cwe_ids": [
"CWE-787"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-04-22T14:16:51Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmodule: Fix kernel panic when a symbol st_shndx is out of bounds\n\nThe module loader doesn\u0027t check for bounds of the ELF section index in\nsimplify_symbols():\n\n for (i = 1; i \u003c symsec-\u003esh_size / sizeof(Elf_Sym); i++) {\n\t\tconst char *name = info-\u003estrtab + sym[i].st_name;\n\n\t\tswitch (sym[i].st_shndx) {\n\t\tcase SHN_COMMON:\n\n\t\t[...]\n\n\t\tdefault:\n\t\t\t/* Divert to percpu allocation if a percpu var. */\n\t\t\tif (sym[i].st_shndx == info-\u003eindex.pcpu)\n\t\t\t\tsecbase = (unsigned long)mod_percpu(mod);\n\t\t\telse\n /** HERE --\u003e **/\t\tsecbase = info-\u003esechdrs[sym[i].st_shndx].sh_addr;\n\t\t\tsym[i].st_value += secbase;\n\t\t\tbreak;\n\t\t}\n\t}\n\nA symbol with an out-of-bounds st_shndx value, for example 0xffff\n(known as SHN_XINDEX or SHN_HIRESERVE), may cause a kernel panic:\n\n BUG: unable to handle page fault for address: ...\n RIP: 0010:simplify_symbols+0x2b2/0x480\n ...\n Kernel panic - not syncing: Fatal exception\n\nThis can happen when module ELF is legitimately using SHN_XINDEX or\nwhen it is corrupted.\n\nAdd a bounds check in simplify_symbols() to validate that st_shndx is\nwithin the valid range before using it.\n\nThis issue was discovered due to a bug in llvm-objcopy, see relevant\ndiscussion for details [1].\n\n[1] https://lore.kernel.org/linux-modules/20251224005752.201911-1-ihor.solodrai@linux.dev/",
"id": "GHSA-h7p4-fpxw-m265",
"modified": "2026-10-15T03:35:39Z",
"published": "2026-04-22T15:31:43Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31521"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/html/ssa-082556.html"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/html/ssa-457936.html"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/082f15d2887329e0f43fd3727e69365f5bfe5d2c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4bbdb0e48176fd281c2b9a211b110db6fd94e175"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5d16f519b6eb1d071807e57efe0df2baa8d32ad6"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6ba6957c640f58dc8ef046981a045da43e47ea23"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ec2b22a58073f80739013588af448ff6e2ab906f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ef75dc1401d8e797ee51559a0dd0336c225e1776"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f9d69d5e7bde2295eb7488a56f094ac8f5383b92"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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