Cloudanix VulnDB

CVE-2024-56673

Medium · 5.5

CVSS

5.5

EPSS

0.2%

Published

Dec 27, 2024

CISA due date

—

Cloudanix analysis

Schedule a fix SSVC: Track

A flaw in how certain RISC-V Linux systems clean up memory mappings can cause the computer to crash when unloading specific drivers or performing memory operations.

Exploitation
Local Privilege
Attacker needs
Local User
Complexity
High
Impact
Denial Of Service
Component
OS kernel
Class
Memory Corruption
Remediation
Patch
Effort
Medium
Patch risk
Low

What it actually does

Incorrect unconditional call to pmd destructor during vmemmap page table teardown on RISC-V SPARSEMEM_VMEMMAP configurations triggers VM_BUG_ON_PAGE and kernel panic.

Why it matters to the business

Systems running affected RISC-V kernels may experience unexpected crashes and reboots during memory hotplug, module unload, or HMM-related operations, leading to downtime and potential data loss in memory-intensive workloads.

How an attack unfolds

An attacker with local access triggers vmemmap_free paths (for example via targeted device driver unload or memory section removal) that reach remove_pgd_mapping without the pmd constructor having run, causing the destructor assertion to fire and panic the kernel.

How to fix it

Update the Linux kernel to commit 344945806f2f7af68be98bac02836c867f223aa9 or later; rebuild and reboot with the patched kernel. For packaged distributions apply the vendor kernel update that contains the equivalent fix.

How to confirm the fix worked

Confirm the running kernel contains commit 344945806f2f7af68be98bac02836c867f223aa9, re-run the HMM selftests that previously reproduced the panic, and verify no BUG_ON occurs during vmemmap teardown.

Typical attack path

  1. Obtain local code execution or user privileges on RISC-V Linux system
  2. Load or unload a kernel module or driver that performs memunmap_pages or sparse section removal
  3. Trigger vmemmap page table teardown code path
  4. Hit unconditional pmd dtor call resulting in BUG and kernel panic

How to detect it

Inspect kernel logs for BUG at include/linux/mm.h mentioning pmd_huge_pte, panics during module unload, and stack traces containing remove_pgd_mapping and vmemmap_free; correlate with RISC-V systems performing HMM or memunmap operations.

What your security team should do

  • Prioritize patching RISC-V systems that use SPARSEMEM_VMEMMAP
  • Apply the referenced upstream commit or distribution kernel update within maintenance windows
  • Monitor for kernel oops or panic reports mentioning remove_pgd_mapping or vmemmap_free
  • Restrict unprivileged module loading until systems are updated

The record

In the Linux kernel, the following vulnerability has been resolved: riscv: mm: Do not call pmd dtor on vmemmap page table teardown The vmemmap's, which is used for RV64 with SPARSEMEM_VMEMMAP, page tables are populated using pmd (page middle directory) hugetables. However, the pmd allocation is not using the generic mechanism used by the VMA code (e.g. pmd_alloc()), or the RISC-V specific create_pgd_mapping()/alloc_pmd_late(). Instead, the vmemmap page table code allocates a page, and calls vmemmap_set_pmd(). This results in that the pmd ctor is *not* called, nor would it make sense to do so. Now, when tearing down a vmemmap page table pmd, the cleanup code would unconditionally, and incorrectly call the pmd dtor, which results in a crash (best case). This issue was found when running the HMM selftests: | tools/testing/selftests/mm# ./test_hmm.sh smoke | ... # when unloading the test_hmm.ko module | page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10915b | flags: 0x1000000000000000(node=0|zone=1) | raw: 1000000000000000 0000000000000000 dead000000000122 0000000000000000 | raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000 | page dumped because: VM_BUG_ON_PAGE(ptdesc->pmd_huge_pte) | ------------[ cut here ]------------ | kernel BUG at include/linux/mm.h:3080! | Kernel BUG [#1] | Modules linked in: test_hmm(-) sch_fq_codel fuse drm drm_panel_orientation_quirks backlight dm_mod | CPU: 1 UID: 0 PID: 514 Comm: modprobe Tainted: G W 6.12.0-00982-gf2a4f1682d07 #2 | Tainted: [W]=WARN | Hardware name: riscv-virtio qemu/qemu, BIOS 2024.10 10/01/2024 | epc : remove_pgd_mapping+0xbec/0x1070 | ra : remove_pgd_mapping+0xbec/0x1070 | epc : ffffffff80010a68 ra : ffffffff80010a68 sp : ff20000000a73940 | gp : ffffffff827b2d88 tp : ff6000008785da40 t0 : ffffffff80fbce04 | t1 : 0720072007200720 t2 : 706d756420656761 s0 : ff20000000a73a50 | s1 : ff6000008915cff8 a0 : 0000000000000039 a1 : 0000000000000008 | a2 : ff600003fff0de20 a3 : 0000000000000000 a4 : 0000000000000000 | a5 : 0000000000000000 a6 : c0000000ffffefff a7 : ffffffff824469b8 | s2 : ff1c0000022456c0 s3 : ff1ffffffdbfffff s4 : ff6000008915c000 | s5 : ff6000008915c000 s6 : ff6000008915c000 s7 : ff1ffffffdc00000 | s8 : 0000000000000001 s9 : ff1ffffffdc00000 s10: ffffffff819a31f0 | s11: ffffffffffffffff t3 : ffffffff8000c950 t4 : ff60000080244f00 | t5 : ff60000080244000 t6 : ff20000000a73708 | status: 0000000200000120 badaddr: ffffffff80010a68 cause: 0000000000000003 | [<ffffffff80010a68>] remove_pgd_mapping+0xbec/0x1070 | [<ffffffff80fd238e>] vmemmap_free+0x14/0x1e | [<ffffffff8032e698>] section_deactivate+0x220/0x452 | [<ffffffff8032ef7e>] sparse_remove_section+0x4a/0x58 | [<ffffffff802f8700>] __remove_pages+0x7e/0xba | [<ffffffff803760d8>] memunmap_pages+0x2bc/0x3fe | [<ffffffff02a3ca28>] dmirror_device_remove_chunks+0x2ea/0x518 [test_hmm] | [<ffffffff02a3e026>] hmm_dmirror_exit+0x3e/0x1018 [test_hmm] | [<ffffffff80102c14>] __riscv_sys_delete_module+0x15a/0x2a6 | [<ffffffff80fd020c>] do_trap_ecall_u+0x1f2/0x266 | [<ffffffff80fde0a2>] _new_vmalloc_restore_context_a0+0xc6/0xd2 | Code: bf51 7597 0184 8593 76a5 854a 4097 0029 80e7 2c00 (9002) 7597 | ---[ end trace 0000000000000000 ]--- | Kernel panic - not syncing: Fatal exception in interrupt Add a check to avoid calling the pmd dtor, if the calling context is vmemmap_free().

Affected packages

Ecosystem Package Introduced Fixed
Debian:13 linux 0 6.12.6-1
Linux Kernel 6.11.0 6.12.6
Ubuntu:14.04:LTS linux 0 3.11.0-12.19
Ubuntu:14.04:LTS linux-aws 0 4.4.0-1002.2
Ubuntu:14.04:LTS linux-azure 0 4.15.0-1023.24~14.04.1
Ubuntu:14.04:LTS linux-lts-xenial 0 4.4.0-13.29~14.04.1
Ubuntu:16.04:LTS linux 0 4.4.0-2.16
Ubuntu:16.04:LTS linux-aws 0 4.4.0-1001.10
Ubuntu:16.04:LTS linux-aws-hwe 0 4.15.0-1030.31~16.04.1
Ubuntu:16.04:LTS linux-azure 0 4.11.0-1009.9
Ubuntu:16.04:LTS linux-gcp 0 4.10.0-1004.4
Ubuntu:16.04:LTS linux-hwe 0 4.8.0-39.42~16.04.1
Ubuntu:16.04:LTS linux-hwe-edge 0 No fix
Ubuntu:16.04:LTS linux-kvm 0 4.4.0-1004.9
Ubuntu:16.04:LTS linux-oracle 0 4.15.0-1007.9~16.04.1
Ubuntu:18.04:LTS linux 0 4.13.0-16.19
Ubuntu:18.04:LTS linux-aws 0 4.15.0-1001.1
Ubuntu:18.04:LTS linux-aws-5.0 0 No fix
Ubuntu:18.04:LTS linux-aws-5.3 0 No fix
Ubuntu:18.04:LTS linux-aws-5.4 0 5.4.0-1018.18~18.04.1
Ubuntu:18.04:LTS linux-azure 0 No fix
Ubuntu:18.04:LTS linux-azure-4.15 0 4.15.0-1082.92
Ubuntu:18.04:LTS linux-azure-5.3 0 No fix
Ubuntu:18.04:LTS linux-azure-5.4 0 5.4.0-1020.20~18.04.1
Ubuntu:18.04:LTS linux-azure-edge 0 No fix
Ubuntu:18.04:LTS linux-gcp 0 No fix
Ubuntu:18.04:LTS linux-gcp-4.15 0 4.15.0-1071.81
Ubuntu:18.04:LTS linux-gcp-5.3 0 No fix
Ubuntu:18.04:LTS linux-gcp-5.4 0 5.4.0-1019.19~18.04.2
Ubuntu:18.04:LTS linux-gke-4.15 0 No fix
Ubuntu:18.04:LTS linux-gke-5.4 0 No fix
Ubuntu:18.04:LTS linux-gkeop-5.4 0 No fix
Ubuntu:18.04:LTS linux-hwe 0 No fix
Ubuntu:18.04:LTS linux-hwe-5.4 0 5.4.0-37.41~18.04.1
Ubuntu:18.04:LTS linux-hwe-edge 0 No fix
Ubuntu:18.04:LTS linux-ibm-5.4 0 5.4.0-1010.11~18.04.2
Ubuntu:18.04:LTS linux-kvm 0 4.15.0-1002.2
Ubuntu:18.04:LTS linux-oem 0 No fix
Ubuntu:18.04:LTS linux-oracle 0 4.15.0-1007.9
Ubuntu:18.04:LTS linux-oracle-5.0 0 No fix
Ubuntu:18.04:LTS linux-oracle-5.3 0 No fix
Ubuntu:18.04:LTS linux-oracle-5.4 0 5.4.0-1019.19~18.04.1
Ubuntu:18.04:LTS linux-raspi-5.4 0 5.4.0-1013.13~18.04.1
Ubuntu:20.04:LTS linux 0 5.4.0-9.12
Ubuntu:20.04:LTS linux-aws 0 5.4.0-1005.5
Ubuntu:20.04:LTS linux-aws-5.11 0 No fix
Ubuntu:20.04:LTS linux-aws-5.13 0 No fix
Ubuntu:20.04:LTS linux-aws-5.15 0 5.15.0-1014.18~20.04.1
Ubuntu:20.04:LTS linux-aws-5.8 0 No fix
Ubuntu:20.04:LTS linux-azure 0 5.4.0-1006.6
Ubuntu:20.04:LTS linux-azure-5.11 0 No fix
Ubuntu:20.04:LTS linux-azure-5.13 0 No fix
Ubuntu:20.04:LTS linux-azure-5.15 0 5.15.0-1007.8~20.04.1
Ubuntu:20.04:LTS linux-azure-5.8 0 No fix
Ubuntu:20.04:LTS linux-azure-fde 0 No fix
Ubuntu:20.04:LTS linux-azure-fde-5.15 0 No fix
Ubuntu:20.04:LTS linux-bluefield 0 5.4.0-1007.10
Ubuntu:20.04:LTS linux-gcp 0 5.4.0-1005.5
Ubuntu:20.04:LTS linux-gcp-5.11 0 No fix
Ubuntu:20.04:LTS linux-gcp-5.13 0 No fix
Ubuntu:20.04:LTS linux-gcp-5.15 0 5.15.0-1006.9~20.04.1
Ubuntu:20.04:LTS linux-gcp-5.8 0 No fix
Ubuntu:20.04:LTS linux-gke 0 No fix
Ubuntu:20.04:LTS linux-gke-5.15 0 No fix
Ubuntu:20.04:LTS linux-gkeop 0 No fix
Ubuntu:20.04:LTS linux-gkeop-5.15 0 No fix
Ubuntu:20.04:LTS linux-hwe-5.11 0 No fix
Ubuntu:20.04:LTS linux-hwe-5.13 0 No fix
Ubuntu:20.04:LTS linux-hwe-5.15 0 5.15.0-33.34~20.04.1
Ubuntu:20.04:LTS linux-hwe-5.8 0 No fix
Ubuntu:20.04:LTS linux-ibm 0 5.4.0-1003.4
Ubuntu:20.04:LTS linux-ibm-5.15 0 5.15.0-1033.36~20.04.1
Ubuntu:20.04:LTS linux-intel-5.13 0 No fix
Ubuntu:20.04:LTS linux-intel-iotg-5.15 0 5.15.0-1003.5~20.04.1
Ubuntu:20.04:LTS linux-iot 0 5.4.0-1001.3
Ubuntu:20.04:LTS linux-kvm 0 5.4.0-1004.4
Ubuntu:20.04:LTS linux-lowlatency-hwe-5.15 0 5.15.0-33.34~20.04.1
Ubuntu:20.04:LTS linux-oem-5.10 0 No fix
Ubuntu:20.04:LTS linux-oem-5.13 0 No fix
Ubuntu:20.04:LTS linux-oem-5.14 0 No fix
Ubuntu:20.04:LTS linux-oem-5.6 0 No fix
Ubuntu:20.04:LTS linux-oracle 0 5.4.0-1005.5
Ubuntu:20.04:LTS linux-oracle-5.11 0 No fix
Ubuntu:20.04:LTS linux-oracle-5.13 0 No fix
Ubuntu:20.04:LTS linux-oracle-5.15 0 5.15.0-1007.9~20.04.1
Ubuntu:20.04:LTS linux-oracle-5.8 0 No fix
Ubuntu:20.04:LTS linux-raspi 0 5.4.0-1007.7
Ubuntu:20.04:LTS linux-raspi2 0 No fix
Ubuntu:20.04:LTS linux-riscv 0 No fix
Ubuntu:20.04:LTS linux-riscv-5.11 0 No fix
Ubuntu:20.04:LTS linux-riscv-5.15 0 5.15.0-1015.17~20.04.1
Ubuntu:20.04:LTS linux-riscv-5.8 0 No fix
Ubuntu:20.04:LTS linux-xilinx-zynqmp 0 5.4.0-1020.24
Ubuntu:22.04:LTS linux 0 5.13.0-19.19
Ubuntu:22.04:LTS linux-allwinner-5.19 0 No fix
Ubuntu:22.04:LTS linux-aws 0 5.13.0-1005.6
Ubuntu:22.04:LTS linux-aws-5.19 0 No fix
Ubuntu:22.04:LTS linux-aws-6.2 0 No fix
Ubuntu:22.04:LTS linux-aws-6.5 0 No fix
Ubuntu:22.04:LTS linux-aws-6.8 0 6.8.0-1009.9~22.04.2
Ubuntu:22.04:LTS linux-azure 0 5.13.0-1006.7
Ubuntu:22.04:LTS linux-azure-5.19 0 No fix
Ubuntu:22.04:LTS linux-azure-6.2 0 No fix
Ubuntu:22.04:LTS linux-azure-6.5 0 No fix
Ubuntu:22.04:LTS linux-azure-6.8 0 6.8.0-1008.8~22.04.1
Ubuntu:22.04:LTS linux-azure-fde 0 No fix
Ubuntu:22.04:LTS linux-azure-fde-5.19 0 No fix
Ubuntu:22.04:LTS linux-azure-fde-6.2 0 No fix
Ubuntu:22.04:LTS linux-gcp 0 5.13.0-1005.6
Ubuntu:22.04:LTS linux-gcp-5.19 0 No fix
Ubuntu:22.04:LTS linux-gcp-6.2 0 No fix
Ubuntu:22.04:LTS linux-gcp-6.5 0 No fix
Ubuntu:22.04:LTS linux-gcp-6.8 0 6.8.0-1010.11~22.04.1
Ubuntu:22.04:LTS linux-gke 0 5.15.0-1002.2
Ubuntu:22.04:LTS linux-gkeop 0 5.15.0-1001.2
Ubuntu:22.04:LTS linux-hwe-5.19 0 No fix
Ubuntu:22.04:LTS linux-hwe-6.2 0 No fix
Ubuntu:22.04:LTS linux-hwe-6.5 0 No fix
Ubuntu:22.04:LTS linux-hwe-6.8 0 6.8.0-38.38~22.04.1
Ubuntu:22.04:LTS linux-ibm 0 5.15.0-1002.2
Ubuntu:22.04:LTS linux-intel-iot-realtime 0 No fix
Ubuntu:22.04:LTS linux-intel-iot-realtime 0 5.15.0-1021.26
Ubuntu:22.04:LTS linux-intel-iotg 0 5.15.0-1004.6
Ubuntu:22.04:LTS linux-kvm 0 5.13.0-1004.4
Ubuntu:22.04:LTS linux-lowlatency 0 5.15.0-22.22
Ubuntu:22.04:LTS linux-lowlatency-hwe-5.19 0 No fix
Ubuntu:22.04:LTS linux-lowlatency-hwe-6.2 0 No fix
Ubuntu:22.04:LTS linux-lowlatency-hwe-6.5 0 No fix
Ubuntu:22.04:LTS linux-lowlatency-hwe-6.8 0 6.8.0-38.38.1~22.04.2
Ubuntu:22.04:LTS linux-nvidia 0 5.15.0-1005.5
Ubuntu:22.04:LTS linux-nvidia-6.2 0 No fix
Ubuntu:22.04:LTS linux-nvidia-6.5 0 No fix
Ubuntu:22.04:LTS linux-nvidia-6.8 0 6.8.0-1008.8~22.04.1
Ubuntu:22.04:LTS linux-oem-5.17 0 No fix
Ubuntu:22.04:LTS linux-oem-6.0 0 No fix
Ubuntu:22.04:LTS linux-oem-6.1 0 No fix
Ubuntu:22.04:LTS linux-oem-6.5 0 No fix
Ubuntu:22.04:LTS linux-oracle 0 5.13.0-1008.10
Ubuntu:22.04:LTS linux-oracle-6.5 0 No fix
Ubuntu:22.04:LTS linux-oracle-6.8 0 6.8.0-1006.6~22.04.3
Ubuntu:22.04:LTS linux-raspi 0 5.13.0-1008.9
Ubuntu:22.04:LTS linux-realtime 0 No fix
Ubuntu:22.04:LTS linux-riscv 0 No fix
Ubuntu:22.04:LTS linux-riscv-5.19 0 No fix
Ubuntu:22.04:LTS linux-riscv-6.5 0 No fix
Ubuntu:22.04:LTS linux-riscv-6.8 0 6.8.0-38.38.1~22.04.1
Ubuntu:22.04:LTS linux-starfive-5.19 0 No fix
Ubuntu:22.04:LTS linux-starfive-6.2 0 No fix
Ubuntu:22.04:LTS linux-starfive-6.5 0 No fix
Ubuntu:22.04:LTS linux-xilinx-zynqmp 0 5.15.0-1022.26
Ubuntu:22.04:LTS:for:NVIDIA:BlueField linux-bluefield 0 5.15.0-1011.13
Ubuntu:24.04:LTS linux 0 6.5.0-9.9
Ubuntu:24.04:LTS linux-aws 0 6.5.0-1008.8
Ubuntu:24.04:LTS linux-azure 0 6.5.0-1007.7
Ubuntu:24.04:LTS linux-gcp 0 6.5.0-1007.7
Ubuntu:24.04:LTS linux-gke 0 6.8.0-1003.5
Ubuntu:24.04:LTS linux-gkeop 0 6.8.0-1001.3
Ubuntu:24.04:LTS linux-hwe-6.11 0 6.11.0-21.21~24.04.1
Ubuntu:24.04:LTS linux-ibm 0 6.5.0-1009.9
Ubuntu:24.04:LTS linux-lowlatency 0 6.5.0-9.9.1
Ubuntu:24.04:LTS linux-nvidia 0 6.8.0-1007.7
Ubuntu:24.04:LTS linux-nvidia-lowlatency 0 6.8.0-1009.9.1
Ubuntu:24.04:LTS linux-oem-6.11 0 No fix
Ubuntu:24.04:LTS linux-oem-6.11 0 6.11.0-1017.17
Ubuntu:24.04:LTS linux-oem-6.8 0 6.8.0-1003.3
Ubuntu:24.04:LTS linux-oracle 0 6.5.0-1010.10
Ubuntu:24.04:LTS linux-raspi 0 6.5.0-1005.7
Ubuntu:24.04:LTS linux-raspi-realtime 0 No fix
Ubuntu:24.04:LTS linux-raspi-realtime 0 6.7.0-2001.1
Ubuntu:24.04:LTS linux-realtime 0 6.8.0-1008.19
Ubuntu:24.04:LTS linux-riscv 0 6.5.0-9.9.1
Ubuntu:24.10 linux 0 No fix
Ubuntu:24.10 linux-aws 0 No fix
Ubuntu:24.10 linux-azure 0 No fix
Ubuntu:24.10 linux-gcp 0 No fix
Ubuntu:24.10 linux-lowlatency 0 No fix
Ubuntu:24.10 linux-lowlatency 0 6.11.0-1011.12
Ubuntu:24.10 linux-oracle 0 No fix
Ubuntu:24.10 linux-raspi 0 No fix
Ubuntu:24.10 linux-raspi 0 6.11.0-1010.10
Ubuntu:24.10 linux-realtime 0 No fix
Ubuntu:24.10 linux-riscv 0 No fix
Ubuntu:Pro:16.04:LTS linux-hwe-edge 0 No fix
Ubuntu:Pro:18.04:LTS linux-aws-5.0 0 No fix
Ubuntu:Pro:18.04:LTS linux-aws-5.3 0 No fix
Ubuntu:Pro:18.04:LTS linux-azure 0 No fix
Ubuntu:Pro:18.04:LTS linux-azure-5.3 0 No fix
Ubuntu:Pro:18.04:LTS linux-azure-edge 0 No fix
Ubuntu:Pro:18.04:LTS linux-gcp 0 No fix
Ubuntu:Pro:18.04:LTS linux-gcp-5.3 0 No fix
Ubuntu:Pro:18.04:LTS linux-gke-4.15 0 No fix
Ubuntu:Pro:18.04:LTS linux-gke-5.4 0 No fix
Ubuntu:Pro:18.04:LTS linux-gkeop-5.4 0 No fix
Ubuntu:Pro:18.04:LTS linux-hwe 0 No fix
Ubuntu:Pro:18.04:LTS linux-hwe-edge 0 No fix
Ubuntu:Pro:18.04:LTS linux-oem 0 No fix
Ubuntu:Pro:18.04:LTS linux-oracle-5.0 0 No fix
Ubuntu:Pro:18.04:LTS linux-oracle-5.3 0 No fix
Ubuntu:Pro:20.04:LTS linux-aws-5.11 0 No fix
Ubuntu:Pro:20.04:LTS linux-aws-5.13 0 No fix

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