ghsa-9r77-32hh-rxf4
Vulnerability from github
Published
2024-09-27 15:30
Modified
2024-10-02 15:30
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: vmalloc: ensure vmap_block is initialised before adding to queue

Commit 8c61291fd850 ("mm: fix incorrect vbq reference in purge_fragmented_block") extended the 'vmap_block' structure to contain a 'cpu' field which is set at allocation time to the id of the initialising CPU.

When a new 'vmap_block' is being instantiated by new_vmap_block(), the partially initialised structure is added to the local 'vmap_block_queue' xarray before the 'cpu' field has been initialised. If another CPU is concurrently walking the xarray (e.g. via vm_unmap_aliases()), then it may perform an out-of-bounds access to the remote queue thanks to an uninitialised index.

This has been observed as UBSAN errors in Android:

| Internal error: UBSAN: array index out of bounds: 00000000f2005512 [#1] PREEMPT SMP | | Call trace: | purge_fragmented_block+0x204/0x21c | _vm_unmap_aliases+0x170/0x378 | vm_unmap_aliases+0x1c/0x28 | change_memory_common+0x1dc/0x26c | set_memory_ro+0x18/0x24 | module_enable_ro+0x98/0x238 | do_init_module+0x1b0/0x310

Move the initialisation of 'vb->cpu' in new_vmap_block() ahead of the addition to the xarray.

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{
   affected: [],
   aliases: [
      "CVE-2024-46847",
   ],
   database_specific: {
      cwe_ids: [
         "CWE-129",
      ],
      github_reviewed: false,
      github_reviewed_at: null,
      nvd_published_at: "2024-09-27T13:15:16Z",
      severity: "MODERATE",
   },
   details: "In the Linux kernel, the following vulnerability has been resolved:\n\nmm: vmalloc: ensure vmap_block is initialised before adding to queue\n\nCommit 8c61291fd850 (\"mm: fix incorrect vbq reference in\npurge_fragmented_block\") extended the 'vmap_block' structure to contain a\n'cpu' field which is set at allocation time to the id of the initialising\nCPU.\n\nWhen a new 'vmap_block' is being instantiated by new_vmap_block(), the\npartially initialised structure is added to the local 'vmap_block_queue'\nxarray before the 'cpu' field has been initialised.  If another CPU is\nconcurrently walking the xarray (e.g.  via vm_unmap_aliases()), then it\nmay perform an out-of-bounds access to the remote queue thanks to an\nuninitialised index.\n\nThis has been observed as UBSAN errors in Android:\n\n | Internal error: UBSAN: array index out of bounds: 00000000f2005512 [#1] PREEMPT SMP\n |\n | Call trace:\n |  purge_fragmented_block+0x204/0x21c\n |  _vm_unmap_aliases+0x170/0x378\n |  vm_unmap_aliases+0x1c/0x28\n |  change_memory_common+0x1dc/0x26c\n |  set_memory_ro+0x18/0x24\n |  module_enable_ro+0x98/0x238\n |  do_init_module+0x1b0/0x310\n\nMove the initialisation of 'vb->cpu' in new_vmap_block() ahead of the\naddition to the xarray.",
   id: "GHSA-9r77-32hh-rxf4",
   modified: "2024-10-02T15:30:37Z",
   published: "2024-09-27T15:30:34Z",
   references: [
      {
         type: "ADVISORY",
         url: "https://nvd.nist.gov/vuln/detail/CVE-2024-46847",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/1b2770e27d6d952f491bb362b657e5b2713c3efd",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/3e3de7947c751509027d26b679ecd243bc9db255",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/6cf74e0e5e3ab5d5c9defb4c73dad54d52224671",
      },
   ],
   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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