Riskcovery

CVE-2024-46847

mm: vmalloc: ensure vmap_block is initialised before adding to queue

State
Published
Severity
7.8 High
Published
Sep 27, 2024
Updated
Aug 5, 2026
Reserved
Sep 11, 2024

Read the record on cve.org

Description

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.

Scores

CVSSScoreVectorSource
3.17.8 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HLinux

Weaknesses

The record names no weakness.

Affected Products

ProductVersions
LinuxLinux
  • 88e0ad40d08a73a74c597e69f4cd2d1fba3838b5 to before 1b2770e27d6d952f491bb362b657e5b2713c3efdAffected
  • 8c61291fd8500e3b35c7ec0c781b273d8cc96cde to before 6cf74e0e5e3ab5d5c9defb4c73dad54d52224671Affected
  • 8c61291fd8500e3b35c7ec0c781b273d8cc96cde to before 3e3de7947c751509027d26b679ecd243bc9db255Affected
  • 9983b81579be3403f5cc44b11f66c6c8bea6547fAffected
  • 6.6.37 to before 6.6.51Affected
  • 6.9.8 to before 6.10Affected
LinuxLinux
  • 6.10Affected
  • before 6.10Not affected
  • 6.6.51 through 6.6.*Not affected
  • 6.10.10 through 6.10.*Not affected
  • 6.11 and laterNot affected

References

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