Attacker Value
Unknown
(0 users assessed)
Exploitability
Unknown
(0 users assessed)
User Interaction
None
Privileges Required
Low
Attack Vector
Local
0

CVE-2024-56613

Disclosure Date: December 27, 2024
Add MITRE ATT&CK tactics and techniques that apply to this CVE.

Description

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

sched/numa: fix memory leak due to the overwritten vma->numab_state

[Problem Description]
When running the hackbench program of LTP, the following memory leak is
reported by kmemleak.

# /opt/ltp/testcases/bin/hackbench 20 thread 1000
Running with 20*40 (== 800) tasks.

# dmesg | grep kmemleak

kmemleak: 480 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
kmemleak: 665 new suspected memory leaks (see /sys/kernel/debug/kmemleak)

# cat /sys/kernel/debug/kmemleak
unreferenced object 0xffff888cd8ca2c40 (size 64):

comm "hackbench", pid 17142, jiffies 4299780315
hex dump (first 32 bytes):
  ac 74 49 00 01 00 00 00 4c 84 49 00 01 00 00 00  .tI.....L.I.....
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
backtrace (crc bff18fd4):
  [<ffffffff81419a89>] __kmalloc_cache_noprof+0x2f9/0x3f0
  [<ffffffff8113f715>] task_numa_work+0x725/0xa00
  [<ffffffff8110f878>] task_work_run+0x58/0x90
  [<ffffffff81ddd9f8>] syscall_exit_to_user_mode+0x1c8/0x1e0
  [<ffffffff81dd78d5>] do_syscall_64+0x85/0x150
  [<ffffffff81e0012b>] entry_SYSCALL_64_after_hwframe+0x76/0x7e

This issue can be consistently reproduced on three different servers:

  • a 448-core server
  • a 256-core server
  • a 192-core server

[Root Cause]
Since multiple threads are created by the hackbench program (along with
the command argument ‘thread’), a shared vma might be accessed by two or
more cores simultaneously. When two or more cores observe that
vma->numab_state is NULL at the same time, vma->numab_state will be
overwritten.

Although current code ensures that only one thread scans the VMAs in a
single ‘numa_scan_period’, there might be a chance for another thread
to enter in the next ‘numa_scan_period’ while we have not gotten till
numab_state allocation [1].

Note that the command /opt/ltp/testcases/bin/hackbench 50 process 1000
cannot the reproduce the issue. It is verified with 200+ test runs.

[Solution]
Use the cmpxchg atomic operation to ensure that only one thread executes
the vma->numab_state assignment.

[1] https://lore.kernel.org/lkml/1794be3c-358c-4cdc-a43d-a1f841d91ef7@amd.com/

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CVSS V3 Severity and Metrics
Base Score:
5.5 Medium
Impact Score:
3.6
Exploitability Score:
1.8
Vector:
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector (AV):
Local
Attack Complexity (AC):
Low
Privileges Required (PR):
Low
User Interaction (UI):
None
Scope (S):
Unchanged
Confidentiality (C):
None
Integrity (I):
None
Availability (A):
High

General Information

Additional Info

Technical Analysis