ghsa-vww8-w2qw-qhfg
Vulnerability from github
Published
2024-12-27 15:31
Modified
2025-01-08 18:30
Severity ?
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Details

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

mm/gup: handle NULL pages in unpin_user_pages()

The recent addition of "pofs" (pages or folios) handling to gup has a flaw: it assumes that unpin_user_pages() handles NULL pages in the pages** array. That's not the case, as I discovered when I ran on a new configuration on my test machine.

Fix this by skipping NULL pages in unpin_user_pages(), just like unpin_folios() already does.

Details: when booting on x86 with "numa=fake=2 movablecore=4G" on Linux 6.12, and running this:

tools/testing/selftests/mm/gup_longterm

...I get the following crash:

BUG: kernel NULL pointer dereference, address: 0000000000000008 RIP: 0010:sanity_check_pinned_pages+0x3a/0x2d0 ... Call Trace: ? __die_body+0x66/0xb0 ? page_fault_oops+0x30c/0x3b0 ? do_user_addr_fault+0x6c3/0x720 ? irqentry_enter+0x34/0x60 ? exc_page_fault+0x68/0x100 ? asm_exc_page_fault+0x22/0x30 ? sanity_check_pinned_pages+0x3a/0x2d0 unpin_user_pages+0x24/0xe0 check_and_migrate_movable_pages_or_folios+0x455/0x4b0 __gup_longterm_locked+0x3bf/0x820 ? mmap_read_lock_killable+0x12/0x50 ? __pfx_mmap_read_lock_killable+0x10/0x10 pin_user_pages+0x66/0xa0 gup_test_ioctl+0x358/0xb20 __se_sys_ioctl+0x6b/0xc0 do_syscall_64+0x7b/0x150 entry_SYSCALL_64_after_hwframe+0x76/0x7e

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{
  "affected": [],
  "aliases": [
    "CVE-2024-56612"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-476"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-12-27T15:15:20Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/gup: handle NULL pages in unpin_user_pages()\n\nThe recent addition of \"pofs\" (pages or folios) handling to gup has a\nflaw: it assumes that unpin_user_pages() handles NULL pages in the pages**\narray.  That\u0027s not the case, as I discovered when I ran on a new\nconfiguration on my test machine.\n\nFix this by skipping NULL pages in unpin_user_pages(), just like\nunpin_folios() already does.\n\nDetails: when booting on x86 with \"numa=fake=2 movablecore=4G\" on Linux\n6.12, and running this:\n\n    tools/testing/selftests/mm/gup_longterm\n\n...I get the following crash:\n\nBUG: kernel NULL pointer dereference, address: 0000000000000008\nRIP: 0010:sanity_check_pinned_pages+0x3a/0x2d0\n...\nCall Trace:\n \u003cTASK\u003e\n ? __die_body+0x66/0xb0\n ? page_fault_oops+0x30c/0x3b0\n ? do_user_addr_fault+0x6c3/0x720\n ? irqentry_enter+0x34/0x60\n ? exc_page_fault+0x68/0x100\n ? asm_exc_page_fault+0x22/0x30\n ? sanity_check_pinned_pages+0x3a/0x2d0\n unpin_user_pages+0x24/0xe0\n check_and_migrate_movable_pages_or_folios+0x455/0x4b0\n __gup_longterm_locked+0x3bf/0x820\n ? mmap_read_lock_killable+0x12/0x50\n ? __pfx_mmap_read_lock_killable+0x10/0x10\n pin_user_pages+0x66/0xa0\n gup_test_ioctl+0x358/0xb20\n __se_sys_ioctl+0x6b/0xc0\n do_syscall_64+0x7b/0x150\n entry_SYSCALL_64_after_hwframe+0x76/0x7e",
  "id": "GHSA-vww8-w2qw-qhfg",
  "modified": "2025-01-08T18:30:47Z",
  "published": "2024-12-27T15:31:55Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-56612"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/69d319450d1c651f3b05cd820ff285fdd810c032"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a1268be280d8e484ab3606d7476edd0f14bb9961"
    }
  ],
  "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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