CVE-2026-46296

What it actually does

This is a Linux kernel denial-of-service flaw in the Samsung S3C64xx SPI controller driver. During driver unbind or controller deregistration, the driver attempts to release a DMA channel that may no longer be allocated, causing a NULL-pointer dereference in kernel context. On affected systems using this SPI controller driver, the result is typically a kernel oops or panic, potentially crashing the device or forcing a reboot. The issue is not known to provide code execution or privilege escalation and is most relevant to systems where the affected SPI driver is present, loaded, and can be unbound or deregistered.

Why it matters to the business

Successful exploitation can make affected Linux-based systems unavailable until they are rebooted or recovered, which is most concerning for embedded devices, appliances, industrial systems, or ARM-based platforms that rely on the S3C64xx SPI controller. Because exploitation generally requires local privileged access or the ability to trigger driver removal, the broad internet-facing risk is low. EPSS is very low and the vulnerability is not in CISA KEV, with no known public exploitation reported, so remediation should be handled through normal kernel update cycles unless the affected driver is used in high-availability or safety-sensitive systems.

How an attack unfolds

An attacker first needs access to a system running an affected Linux kernel with the s3c64xx SPI controller driver active. In the most plausible scenario, the attacker already has local administrative privileges, CAP_SYS_ADMIN-equivalent capabilities, or control over a management path that can unbind kernel platform drivers, unload modules, or trigger controller deregistration. The attacker then causes the affected SPI driver to be unbound or removed. During the remove path, the kernel executes cleanup logic that attempts to release a DMA channel pointer that is NULL. This causes a kernel NULL-pointer dereference, resulting in an oops or panic depending on kernel configuration, which can crash the system or disrupt services hosted on the device.

How to fix it

Apply a Linux kernel update that includes the upstream fix for the s3c64xx SPI driver remove path, which removes the invalid DMA channel release during driver unbind. If vendor packages are used, update to the kernel version supplied by the Linux distribution, device vendor, or board support package maintainer that contains the fix. If immediate patching is not possible, reduce exposure by preventing untrusted users or workloads from gaining privileges capable of writing to driver unbind interfaces, unloading kernel modules, or managing platform devices. On systems that do not require this driver, consider disabling or not loading the s3c64xx SPI driver through kernel configuration, module policy, or platform configuration. For high-availability embedded systems, schedule maintenance windows for kernel replacement and reboot validation.

How to confirm the fix worked

Confirm the running kernel includes the vendor or upstream fix for the s3c64xx SPI driver. Review kernel package changelogs, distribution advisories, or source code to verify that the erroneous DMA channel release was removed from the driver remove path. On source-based or custom kernels, inspect the relevant s3c64xx SPI driver implementation and confirm the remove/unbind path no longer releases a possibly NULL DMA channel allocated elsewhere. Validate exposure by checking whether the s3c64xx SPI driver is built into the kernel, loaded as a module, or bound to a platform device. After patching, perform controlled regression testing of SPI functionality and, if safe in a lab environment, driver unbind/rebind behavior to confirm no kernel oops or panic occurs.

Typical attack path

1. Identify a Linux system or embedded device using the affected s3c64xx SPI controller driver.
2. Obtain local privileged access, container escape to sufficient kernel-management capabilities, physical/service access, or another path able to trigger driver unbind/removal.
3. Trigger driver unbind, module removal, or controller deregistration for the affected SPI controller.
4. The driver remove path attempts to release a non-existent DMA channel and dereferences a NULL pointer.
5. The kernel logs an oops or panic and the system may crash, reboot, or require manual recovery.

How to detect it

To assess whether this was already triggered, review kernel logs and persistent crash logs for NULL-pointer dereference, oops, panic, or reboot events occurring during SPI driver removal, platform device deregistration, module unload, or sysfs driver unbind activity. Relevant log sources include journalctl kernel logs, /var/log/kern.log, /var/log/messages, dmesg output, pstore/ramoops records, kdump/vmcore artifacts, crash dump summaries, and device-management/audit logs showing writes to sysfs driver unbind paths. Look for stack traces mentioning the s3c64xx SPI driver remove/unbind path or DMA channel release routines near the time of an unexpected reboot. Because this vulnerability causes a crash rather than persistent compromise, there may be no file-system artifact beyond kernel crash evidence and administrative activity that triggered driver unbind/removal.

• s3c64xx
• s3c64xx-spi
• s3c64xx_spi
• s3c64xx_spi_remove
• NULL pointer dereference
• Unable to handle kernel NULL pointer dereference
• BUG: kernel NULL pointer dereference
• Kernel panic - not syncing
• Oops:
• dma_release_channel
• /sys/bus/platform/drivers/s3c64xx-spi/unbind
• /sys/bus/platform/drivers/*/unbind
• driver unbind
• ramoops
• pstore
• vmcore

What your security team should do

• Inventory Linux and embedded devices for use of the s3c64xx SPI controller driver, prioritizing ARM-based appliances and board support package kernels.
• Patch affected kernels during the next regular maintenance cycle, or sooner for systems where a crash would cause operational outage or safety impact.
• Restrict privileged local access and administrative interfaces that can unbind drivers, unload modules, or manage platform devices.
• For containerized environments, ensure containers do not have unnecessary privileged mode, host device access, CAP_SYS_ADMIN, or write access to sysfs driver controls.
• Monitor kernel logs for NULL-pointer dereference, kernel oops, panic, or crash events involving the s3c64xx SPI driver.
• For custom kernels, backport the upstream driver fix and perform targeted SPI controller unbind/rebind regression testing before deployment.