CVE-2026-80648 in Linux
Summary
by MITRE • 08/28/2026
In the Linux kernel, the following vulnerability has been resolved:
pinctrl: spacemit: fix NULL check in spacemit_pin_set_config
spacemit_pin_set_config() looks up the per-pin descriptor with spacemit_get_pin() then checks the wrong variable for failure:
const struct spacemit_pin *spin = spacemit_get_pin(pctrl, pin); ... if (!pin) return -EINVAL;
reg = spacemit_pin_to_reg(pctrl, spin->pin);
pin is an unsigned int pin id, where 0 (GPIO_0 / gmac0_rxdv on K3) is a valid pin, so rejecting it here drops the PAD config write for the first pin of every group. On K3 Pico-ITX the GMAC RGMII group lists pin 0 as its first entry, so its drive-strength / bias configuration was silently ignored.
The intended guard is against spacemit_get_pin() returning NULL when the pin id isn't in the SoC's pin table. Check spin instead, which both restores PAD setup for pin 0 and prevents a NULL deref on spin->pin.
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Analysis
by VulDB Data Team • 08/28/2026
The Linux kernel pinctrl subsystem manages the configuration of physical pins on system-on-chip devices, including parameters such as drive strength, biasing, and electrical characteristics. A critical logic error was identified within the spacemit pin control driver, specifically in the function responsible for setting per-pin configurations. This vulnerability stems from a copy-paste or variable naming oversight where the code checks an incorrect pointer for nullity after attempting to retrieve a pin descriptor. The function spacemit_pin_set_config is designed to look up the specific pin configuration structure by calling spacemit_get_pin with the provided controller and pin identifier. Upon retrieval, the developer intended to verify that this lookup was successful before proceeding to apply hardware-specific settings. However, the conditional check erroneously validates the original input variable representing the numeric pin ID rather than the pointer returned by the lookup function.
This flaw results in two distinct operational failures depending on the specific pin being configured. First, because the checked variable is an unsigned integer identifier for a physical pin, and zero represents a valid GPIO number such as GMAC0_RXDV on certain K3 series chips, the condition fails to trigger when it should not. Consequently, any configuration request targeting pin zero is silently discarded by the driver logic. This leads to hardware misconfiguration where critical peripherals like Ethernet interfaces may operate with default or undefined electrical characteristics rather than the intended drive strength and bias settings. Such silent failures can cause intermittent connectivity issues, signal integrity problems, or complete peripheral malfunction in production environments without generating obvious error logs that would alert system administrators.
Secondly, when spacemit_get_pin fails to find a valid pin descriptor because the requested identifier does not exist in the SoC's pin table, it returns NULL. Since the code checks the wrong variable for nullity, this failure condition is ignored. The execution flow continues to dereference the spin pointer to access its members, specifically accessing spin->pin within spacemit_pin_to_reg. This results in a kernel NULL pointer dereference, which typically causes an immediate system crash or panic on most architectures. This represents a severe stability risk that can be triggered by any user-space application or driver attempting to configure a non-existent pin number, effectively allowing local denial of service through simple API misuse.
From a vulnerability classification perspective, this issue aligns with CWE-476, which describes a NULL pointer dereference resulting from improper validation of function return values. Additionally, the logic error regarding valid input ranges relates closely to CWE-839, where a numeric value is used in a comparison that allows out-of-bounds or invalid states due to incorrect boundary checks. In terms of attack vectors and detection methods within the MITRE ATT&CK framework for enterprise environments, this type of kernel-level instability falls under T1055, specifically processes injecting into or exploiting local vulnerabilities to cause service disruption. While not directly exploitable for privilege escalation in its current form due to the crash nature, it significantly impacts system availability and reliability.
Mitigation strategies primarily involve applying the upstream Linux kernel patch that corrects the variable reference in spacemit_pin_set_config. System administrators managing devices based on Spacemit K3 series SoCs should ensure their kernels are updated to versions containing this fix. For organizations unable to immediately update, monitoring for kernel panics or oops logs related to pinctrl drivers can help identify affected systems. Long-term remediation includes enforcing static analysis tools that detect mismatched variable checks in pointer retrieval patterns and conducting code reviews focused on distinguishing between input identifiers and returned object pointers to prevent similar logical errors in future driver development cycles.