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GHSA-CXF4-996M-V4M3

Vulnerability from github – Published: 2024-07-12 15:31 – Updated: 2025-11-04 00:30
VLAI
Details

In the Linux kernel, the following vulnerability has been resolved:

riscv: rewrite __kernel_map_pages() to fix sleeping in invalid context

__kernel_map_pages() is a debug function which clears the valid bit in page table entry for deallocated pages to detect illegal memory accesses to freed pages.

This function set/clear the valid bit using __set_memory(). __set_memory() acquires init_mm's semaphore, and this operation may sleep. This is problematic, because __kernel_map_pages() can be called in atomic context, and thus is illegal to sleep. An example warning that this causes:

BUG: sleeping function called from invalid context at kernel/locking/rwsem.c:1578 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 2, name: kthreadd preempt_count: 2, expected: 0 CPU: 0 PID: 2 Comm: kthreadd Not tainted 6.9.0-g1d4c6d784ef6 #37 Hardware name: riscv-virtio,qemu (DT) Call Trace: [] dump_backtrace+0x1c/0x24 [] show_stack+0x2c/0x38 [] dump_stack_lvl+0x5a/0x72 [] dump_stack+0x14/0x1c [] __might_resched+0x104/0x10e [] __might_sleep+0x3e/0x62 [] down_write+0x20/0x72 [] __set_memory+0x82/0x2fa [] __kernel_map_pages+0x5a/0xd4 [] __alloc_pages_bulk+0x3b2/0x43a [] __vmalloc_node_range+0x196/0x6ba [] copy_process+0x72c/0x17ec [] kernel_clone+0x60/0x2fe [] kernel_thread+0x82/0xa0 [] kthreadd+0x14a/0x1be [] ret_from_fork+0xe/0x1c

Rewrite this function with apply_to_existing_page_range(). It is fine to not have any locking, because __kernel_map_pages() works with pages being allocated/deallocated and those pages are not changed by anyone else in the meantime.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2024-40915"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-667"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-07-12T13:15:14Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nriscv: rewrite __kernel_map_pages() to fix sleeping in invalid context\n\n__kernel_map_pages() is a debug function which clears the valid bit in page\ntable entry for deallocated pages to detect illegal memory accesses to\nfreed pages.\n\nThis function set/clear the valid bit using __set_memory(). __set_memory()\nacquires init_mm\u0027s semaphore, and this operation may sleep. This is\nproblematic, because  __kernel_map_pages() can be called in atomic context,\nand thus is illegal to sleep. An example warning that this causes:\n\nBUG: sleeping function called from invalid context at kernel/locking/rwsem.c:1578\nin_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 2, name: kthreadd\npreempt_count: 2, expected: 0\nCPU: 0 PID: 2 Comm: kthreadd Not tainted 6.9.0-g1d4c6d784ef6 #37\nHardware name: riscv-virtio,qemu (DT)\nCall Trace:\n[\u003cffffffff800060dc\u003e] dump_backtrace+0x1c/0x24\n[\u003cffffffff8091ef6e\u003e] show_stack+0x2c/0x38\n[\u003cffffffff8092baf8\u003e] dump_stack_lvl+0x5a/0x72\n[\u003cffffffff8092bb24\u003e] dump_stack+0x14/0x1c\n[\u003cffffffff8003b7ac\u003e] __might_resched+0x104/0x10e\n[\u003cffffffff8003b7f4\u003e] __might_sleep+0x3e/0x62\n[\u003cffffffff8093276a\u003e] down_write+0x20/0x72\n[\u003cffffffff8000cf00\u003e] __set_memory+0x82/0x2fa\n[\u003cffffffff8000d324\u003e] __kernel_map_pages+0x5a/0xd4\n[\u003cffffffff80196cca\u003e] __alloc_pages_bulk+0x3b2/0x43a\n[\u003cffffffff8018ee82\u003e] __vmalloc_node_range+0x196/0x6ba\n[\u003cffffffff80011904\u003e] copy_process+0x72c/0x17ec\n[\u003cffffffff80012ab4\u003e] kernel_clone+0x60/0x2fe\n[\u003cffffffff80012f62\u003e] kernel_thread+0x82/0xa0\n[\u003cffffffff8003552c\u003e] kthreadd+0x14a/0x1be\n[\u003cffffffff809357de\u003e] ret_from_fork+0xe/0x1c\n\nRewrite this function with apply_to_existing_page_range(). It is fine to\nnot have any locking, because __kernel_map_pages() works with pages being\nallocated/deallocated and those pages are not changed by anyone else in the\nmeantime.",
  "id": "GHSA-cxf4-996m-v4m3",
  "modified": "2025-11-04T00:30:53Z",
  "published": "2024-07-12T15:31:27Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-40915"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8661a7af04991201640863ad1a0983173f84b5eb"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/919f8626099d9909b9a9620b05e8c8ab06581876"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d5257ceb19d92069195254866421f425aea42915"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fb1cf0878328fe75d47f0aed0a65b30126fcefc4"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html"
    }
  ],
  "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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