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Linux Kernel EUVDEUVD-2026-32783

| CVE-2026-46156 MEDIUM
Improper Locking (CWE-667)
2026-05-28 416baaa9-dc9f-4396-8d5f-8c081fb06d67 GHSA-vmw4-6x55-pgfq
Information Disclosure Linux Red Hat Suse
5.5
CVSS 3.1 · NVD
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Severity by source

NVD PRIMARY
5.5 MEDIUM
AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
SUSE
4.4 MEDIUM
AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

Primary rating from NVD.

CVSS VectorNVD

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

5
Analysis Generated
Jun 09, 2026 - 23:26 vuln.today
CVSS changed
Jun 09, 2026 - 21:07 NVD
5.5 (MEDIUM)
Patch available
May 28, 2026 - 12:01 EUVD
CVE Published
May 28, 2026 - 10:16 nvd
MEDIUM 5.5
CVE Published
May 28, 2026 - 10:16 nvd
UNKNOWN (no severity yet)

DescriptionCVE.org

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

AnalysisAI

Kernel panic (ADE - Address Error for Memory access) in the LoongArch-specific PCI fixup function loongson_gpu_fixup_dma_hang() crashes systems that boot with a discrete Loongson GPU whose PCI device ID does not match any handled case in the switch statement. The missing default case causes readl() to be called with a garbage MMIO address derived from uninitialized register state, resulting in a hard kernel panic at boot time (PID 1, swapper/0) and rendering the system unavailable. No public exploit identified at time of analysis, and EPSS is 0.02% (5th percentile), consistent with a hardware-specific local DoS requiring no attacker interaction.

Technical ContextAI

The affected code resides in the LoongArch architecture-specific PCI quirk subsystem of the Linux kernel (cpe:2.3:o:linux:linux_kernel). The function loongson_gpu_fixup_dma_hang() is registered as a PCI fixup that fires during pci_setup_device() when the PCI bus is enumerated via ACPI. It computes a 'base' address from pdev->devfn+1 and derives a 'device' identifier from base+PCI_DEVICE_ID. A switch statement then dispatches on the device value to set crtc_reg for a subsequent readl() MMIO read. However, when a discrete GPU such as the Loongson LG100 (bus 06.0) is present, its device ID matches no case (DC2 or DC3), so crtc_reg is never initialized and readl() is called with whatever value happened to be in the register - in the captured trace, 0x7fffffffffffff00 (the value from s1), producing ESTAT: [ADEM] (address error for memory access). The CWE-667 (Improper Locking) classification assigned by NVD does not accurately reflect the root cause, which is a missing default branch in a switch statement causing use of an uninitialized pointer - closer in nature to CWE-20 (Improper Input Validation) or CWE-476. The 'Information Disclosure' tag in the source intelligence is also inconsistent with the CVSS impact scores (C:N/I:N/A:H), which correctly describe a pure availability impact.

RemediationAI

Upgrade to a fixed Linux kernel version: 6.6.140, 6.12.88, 6.18.30, 7.0.7, or 7.1-rc3 per vendor-released patch availability confirmed by EUVD. The fix adds a default branch to the switch statement in loongson_gpu_fixup_dma_hang() so that unrecognized PCI device IDs result in a safe no-op rather than an uninitialized MMIO read. Fix commits are published at https://git.kernel.org/stable/c/07d190e4ec689d6478f7f5e36099fb9bf457e7c5 and related stable-tree commits. For LoongArch system operators who cannot patch immediately, a specific compensating control is to blacklist the loongson_gpu_fixup_dma_hang PCI fixup by passing 'pci=nofixups' on the kernel command line - note this disables all PCI quirks and may cause other hardware-specific DMA hang workarounds to be skipped, so it should be treated as a temporary measure only. Alternatively, removing or not inserting the discrete GPU (specifically any Loongson GPU whose PCI device ID is not the DC2 or DC3 controller) eliminates the trigger entirely until a patched kernel is deployed.

Same weakness CWE-667 – Improper Locking

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Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
openSUSE Tumbleweed Fixed
SUSE Linux Enterprise Desktop 15 SP7 Not-Affected
SUSE Linux Enterprise Desktop 15 SP7 Not-Affected
SUSE Linux Enterprise High Availability Extension 15 SP7 Not-Affected
SUSE Linux Enterprise High Availability Extension 15 SP7 Not-Affected

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EUVD-2026-32783 vulnerability details – vuln.today
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