# CVE-2026-46156: LoongArch: Fix potential ADE in loongson_gpu_fixup_dma_hang()

> A missing default case in the LoongArch GPU driver causes a kernel panic when accessing invalid memory addresses, leading to system denial of service.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 28 May 2026
- **Updated:** 14 Jun 2026
- **Also known as:** AZL-89121, BELL-CVE-2026-46156, DEBIAN-CVE-2026-46156, GHSA-vmw4-6x55-pgfq, ROOT-OS-DEBIAN-12-CVE-2026-46156, UBUNTU-CVE-2026-46156

## What is CVE-2026-46156?

CVE-2026-46156 is a medium-severity vulnerability in Linux kernel, published on 28 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

LoongArch: Fix potential ADE in loongson_gpu_fixup_dma_hang()

The switch case in loongson_gpu_fixup_dma_hang() may not DC2 or DC3, and
readl(crtc_reg) will access with random address, because the "device" is
from "base+PCI_DEVICE_ID", "base" is from "pdev->devfn+1". This is wrong
when my platform inserts a discrete GPU:

lspci -tv
-[0000:00]-+-00.0  Loongson Technology LLC Hyper Transport Bridge Controller
...
           +-06.0  Loongson Technology LLC LG100 GPU
           +-06.2  Loongson Technology LLC Device 7a37
...

Add a default switch case to fix the panic as below:

 Kernel ade access[#1]:
 CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.6.136-loong64-desktop-hwe+ #4
 pc 90000000017e5534 ra 90000000017e54c0 tp 90000001002f8000 sp 90000001002fb6c0
 a0 80000efe00003100 a1 0000000000003100 a2 0000000000000000 a3 0000000000000002
 a4 90000001002fb6b4 a5 900000087cdb58fd a6 90000000027af000 a7 0000000000000001
 t0 00000000000085b9 t1 000000000000ffff t2 0000000000000000 t3 0000000000000000
 t4 fffffffffffffffd t5 00000000fffb6d9c t6 0000000000083b00 t7 00000000000070c0
 t8 900000087cdb4d94 u0 900000087cdb58fd s9 90000001002fb826 s0 90000000031c12c8
 s1 7fffffffffffff00 s2 90000000031c12d0 s3 0000000000002710 s4 0000000000000000
 s5 0000000000000000 s6 9000000100053000 s7 7fffffffffffff00 s8 90000000030d4000
    ra: 90000000017e54c0 loongson_gpu_fixup_dma_hang+0x40/0x210
   ERA: 90000000017e5534 loongson_gpu_fixup_dma_hang+0xb4/0x210
  CRMD: 000000b0 (PLV0 -IE -DA +PG DACF=CC DACM=CC -WE)
  PRMD: 00000004 (PPLV0 +PIE -PWE)
  EUEN: 00000000 (-FPE -SXE -ASXE -BTE)
  ECFG: 00071c1d (LIE=0,2-4,10-12 VS=7)
 ESTAT: 00480000 [ADEM] (IS= ECode=8 EsubCode=1)
  BADV: 7fffffffffffff00
  PRID: 0014d000 (Loongson-64bit, Loongson-3A6000-HV)
 Modules linked in:
 Process swapper/0 (pid: 1, threadinfo=(____ptrval____), task=(____ptrval____))
 Stack : 0000000000000006 90000001002fb778 90000001002fb704 0000000000000007
         0000000016a65700 90000000017e5690 000000000000ffff ffffffffffffffff
         900000000209f7c0 9000000100053000 900000000209f7a8 9000000000eebc08
         0000000000000000 0000000000000000 0000000000000006 90000001002fb778
         90000001000530b8 90000000027af000 0000000000000000 9000000100054000
         9000000100053000 9000000000ebb70c 9000000100004c00 9000000004000001
         90000001002fb7e4 bae765461f31cb12 0000000000000000 0000000000000000
         0000000000000006 90000000027af000 0000000000000030 90000000027af000
         900000087cd6f800 9000000100053000 0000000000000000 9000000000ebc560
         7a2500147cdaf720 bae765461f31cb12 0000000000000001 0000000000000030
         ...
 Call Trace:
 [<90000000017e5534>] loongson_gpu_fixup_dma_hang+0xb4/0x210
 [<9000000000eebc08>] pci_fixup_device+0x108/0x280
 [<9000000000ebb70c>] pci_setup_device+0x24c/0x690
 [<9000000000ebc560>] pci_scan_single_device+0xe0/0x140
 [<9000000000ebc684>] pci_scan_slot+0xc4/0x280
 [<9000000000ebdd00>] pci_scan_child_bus_extend+0x60/0x3f0
 [<9000000000f5bc94>] acpi_pci_root_create+0x2b4/0x420
 [<90000000017e5e74>] pci_acpi_scan_root+0x2d4/0x440
 [<9000000000f5b02c>] acpi_pci_root_add+0x21c/0x3a0
 [<9000000000f4ee54>] acpi_bus_attach+0x1a4/0x3c0
 [<90000000010e200c>] device_for_each_child+0x6c/0xe0
 [<9000000000f4bbf4>] acpi_dev_for_each_child+0x44/0x70
 [<9000000000f4ef40>] acpi_bus_attach+0x290/0x3c0
 [<90000000010e200c>] device_for_each_child+0x6c/0xe0
 [<9000000000f4bbf4>] acpi_dev_for_each_child+0x44/0x70
 [<9000000000f4ef40>] acpi_bus_attach+0x290/0x3c0
 [<9000000000f5211c>] acpi_bus_scan+0x6c/0x280
 [<900000000189c028>] acpi_scan_init+0x194/0x310
 [<900000000189bc6c>] acpi_init+0xcc/0x140
 [<9000000000220cdc>] do_one_initcall+0x4c/0x310
 [<90000000018618fc>] kernel_init_freeable+0x258/0x2d4
 [<900000000184326c>] kernel_init+0x28/0x13c
 [<9000000000222008>] ret_from_kernel_thread+0xc/0xa4

Weakness: CWE-667 (Improper Locking)

## Which versions are affected by CVE-2026-46156?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-46156?

Apply the vendor's patch.

## Is CVE-2026-46156 being exploited?

There is no known exploitation of CVE-2026-46156 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-46156 and fix it if it is affected.

What it is: CVE-2026-46156 is a medium-severity vulnerability in Linux kernel, published on 28 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-46156 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-46156/ (Markdown: https://insights.sbomify.com/CVE-2026-46156/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-46156
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-46156
- OSV: https://osv.dev/vulnerability/CVE-2026-46156

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-46156/
Summaries are generated and may contain mistakes; the official description above is the record.