ghsa-h48v-q4mj-95wg
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
arm64: mm: Fix lockless walks with static and dynamic page-table folding
Lina reports random oopsen originating from the fast GUP code when 16K pages are used with 4-level page-tables, the fourth level being folded at runtime due to lack of LPA2.
In this configuration, the generic implementation of p4d_offset_lockless() will return a 'p4d_t *' corresponding to the 'pgd_t' allocated on the stack of the caller, gup_fast_pgd_range(). This is normally fine, but when the fourth level of page-table is folded at runtime, pud_offset_lockless() will offset from the address of the 'p4d_t' to calculate the address of the PUD in the same page-table page. This results in a stray stack read when the 'p4d_t' has been allocated on the stack and can send the walker into the weeds.
Fix the problem by providing our own definition of p4d_offset_lockless() when CONFIG_PGTABLE_LEVELS <= 4 which returns the real page-table pointer rather than the address of the local stack variable.
{
"affected": [],
"aliases": [
"CVE-2024-42293"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-08-17T09:15:09Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\narm64: mm: Fix lockless walks with static and dynamic page-table folding\n\nLina reports random oopsen originating from the fast GUP code when\n16K pages are used with 4-level page-tables, the fourth level being\nfolded at runtime due to lack of LPA2.\n\nIn this configuration, the generic implementation of\np4d_offset_lockless() will return a \u0027p4d_t *\u0027 corresponding to the\n\u0027pgd_t\u0027 allocated on the stack of the caller, gup_fast_pgd_range().\nThis is normally fine, but when the fourth level of page-table is folded\nat runtime, pud_offset_lockless() will offset from the address of the\n\u0027p4d_t\u0027 to calculate the address of the PUD in the same page-table page.\nThis results in a stray stack read when the \u0027p4d_t\u0027 has been allocated\non the stack and can send the walker into the weeds.\n\nFix the problem by providing our own definition of p4d_offset_lockless()\nwhen CONFIG_PGTABLE_LEVELS \u003c= 4 which returns the real page-table\npointer rather than the address of the local stack variable.",
"id": "GHSA-h48v-q4mj-95wg",
"modified": "2024-08-17T09:30:24Z",
"published": "2024-08-17T09:30:24Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-42293"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/36639013b3462c06ff8e3400a427f775b4fc97f5"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/78672d49d3eebbcda3589f4d6e589caf357c5a59"
}
],
"schema_version": "1.4.0",
"severity": []
}
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- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.