GHSA-3RVR-4RPW-5W37
Vulnerability from github – Published: 2026-09-17 18:32 – Updated: 2026-09-17 18:32In the Linux kernel, the following vulnerability has been resolved:
ARM: 9485/1: mm: acquire mmap write lock around show_pte() for user faults
When CONFIG_DEBUG_USER=y, and cmdline "user_debug=31" is set, a user fault may trigger show_pte() without any lock. If another thread in the same process concurrently calls munmap(), the page table pages may be freed while show_pte() is still traversing them, causing a use-after-free in show_pte().
If CONFIG_ARM_LPAE=y, this may cause a kernel panic if the pages table of PMD are freed when show_pte() is running.
Acquire mmap_write_lock() around show_pte() for user faults to fix the contention.
For user faults, additionally restrict that show_pte() is called only when the addr is a user-space address (addr < TASK_SIZE). This is because the lock of tsk->mm only protects the virtual memory of user address space, furthermore, dumping the page tables of a kernel-space address for user faults is unnecessary and may have security implications.
Keep everything unchanged for kernel faults, because the kernel is already in the "oops" state, acquiring a lock may risk a deadlock.
{
"affected": [],
"aliases": [
"CVE-2026-90303"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-17T17:17:27Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nARM: 9485/1: mm: acquire mmap write lock around show_pte() for user faults\n\nWhen CONFIG_DEBUG_USER=y, and cmdline \"user_debug=31\" is set,\na user fault may trigger show_pte() without any lock.\nIf another thread in the same process concurrently calls munmap(),\nthe page table pages may be freed while show_pte() is still traversing\nthem, causing a use-after-free in show_pte().\n\nIf CONFIG_ARM_LPAE=y, this may cause a kernel panic if the pages table\nof PMD are freed when show_pte() is running.\n\nAcquire mmap_write_lock() around show_pte() for user faults to fix the\ncontention.\n\nFor user faults, additionally restrict that show_pte() is called only\nwhen the addr is a user-space address (addr \u003c TASK_SIZE). This is because\nthe lock of tsk-\u003emm only protects the virtual memory of user address space,\nfurthermore, dumping the page tables of a kernel-space address for user\nfaults is unnecessary and may have security implications.\n\nKeep everything unchanged for kernel faults, because the kernel is\nalready in the \"oops\" state, acquiring a lock may risk a deadlock.",
"id": "GHSA-3rvr-4rpw-5w37",
"modified": "2026-09-17T18:32:00Z",
"published": "2026-09-17T18:32:00Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-90303"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/07e4d5380f2a844ab7a1b440dde350caf561cbb0"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1039bffd6ae9c75b42b7d148d6c1106134107b66"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2a14d7797a49a47bccd1a9327fd69da838dcb0dd"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/59bbf86d0ff9373bfa033ca123c1e924f09f1eba"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/63e3c958a602d0896a101a897c2361878c266ca7"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/720408d98d9fb3c91a12090436734c8c61f04545"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ab14f07952adfe735d86a53518f8cd576dfd5892"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c71f9a56520b419e55d173052629f2324deb5549"
}
],
"schema_version": "1.4.0",
"severity": []
}
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