CVE-2026-98605 in Linux
Summary
by MITRE • 10/18/2026
In the Linux kernel, the following vulnerability has been resolved:
drm/bridge: samsung-dsim: fix TE GPIO lifetime for host attach
When the Exynos DSI driver was generalized into samsung-dsim, the TE GPIO acquisition was switched from gpiod_get_optional() to devm_gpiod_get_optional() while keeping the matching gpiod_put() calls. That combination is wrong for a managed descriptor.
However, dropping the puts and keeping the managed get is also wrong: samsung_dsim_register_te_irq() runs from the DSI host attach callback, and host detach/reattach can happen without destroying the device that owns the managed action. A second attach would then request the GPIO again without having released it.
Switch back to a non-managed gpiod_get_optional() and keep the explicit gpiod_put() on the request_irq() error path and in samsung_dsim_unregister_te_irq().
[Luca: remove unnecessary comment]
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Analysis
by VulDB Data Team • 10/18/2026
The vulnerability identified within the Linux kernel's DRM bridge subsystem, specifically affecting the Samsung DSI driver component known as samsung-dsim, stems from an incorrect management of General Purpose Input/Output (GPIO) resource lifecycles during device attachment and detachment operations. This issue originated when the Exynos Display Serial Interface driver was refactored into a more generalized framework called samsung-dsi. During this transition, developers modified how the Tear Effect GPIO descriptor is acquired, switching from an unmanaged function call to one that utilizes managed resources via devm_gpiod_get_optional(). However, the corresponding cleanup logic retained explicit calls to gpiod_put(), which creates a fundamental conflict in resource management semantics because managed descriptors are automatically released when their associated device is destroyed.
The core technical flaw lies in the mismatch between the acquisition method and the release strategy for the GPIO descriptor. When devm_gpiod_get_optional() is used, the kernel's device resource management subsystem assumes ownership of the descriptor and will handle its deallocation upon device removal. By retaining manual gpiod_put() calls, the code attempts to free a resource that it no longer owns or should not manually manage in this context. This inconsistency leads to undefined behavior, potentially resulting in double-free errors if the managed system also releases the resource, or use-after-free scenarios where the descriptor is accessed after being improperly freed by one of the conflicting mechanisms.
Beyond immediate memory corruption risks, this flaw has significant operational implications for device stability and reliability during dynamic reconfiguration events. The samsung_dsim_register_te_irq function operates within the DSI host attach callback, which can be triggered multiple times without a full device teardown occurring in between. Specifically, scenarios involving host detach and subsequent reattach allow the system to request GPIO resources again while previous instances may not have been correctly released due to the flawed management logic. This situation creates a race condition or resource leak where repeated attachment cycles accumulate unreleased or improperly managed descriptors, eventually exhausting available GPIO handles or causing kernel panics during hotplug events such as display cable insertion and removal.
From a security perspective, this vulnerability aligns with CWE-416, Use After Free, due to the potential for accessing freed memory structures if the double-free occurs in a way that leaves dangling pointers. It also relates to CWE-772, Missing Release of Resource after Effective Lifetime, as the improper handling can lead to resource exhaustion over time during repeated attach/detach cycles. In terms of adversary behavior and detection frameworks like MITRE ATT&CK, while this is primarily a stability issue rather than an exploitable privilege escalation vector in most standard configurations, it falls under T1499, Endpoint Denial of Service, as successful exploitation through rapid reattachment loops could crash the kernel or render the display subsystem non-functional.
To mitigate this vulnerability and restore correct resource lifecycle management, the fix involves reverting to unmanaged GPIO acquisition functions while ensuring explicit cleanup on error paths and during proper deregistration. The solution switches back to using gpiod_get_optional() instead of its managed counterpart, thereby giving the driver direct control over when the descriptor is released. Crucially, this change ensures that gpiod_put() is called only in appropriate contexts, specifically on the request_irq() error path where allocation fails but partial setup has occurred, and within samsung_dsim_unregister_te_irq() during normal device teardown. This approach guarantees that resources are freed exactly once at the correct time, preventing both leaks and double-free errors while maintaining compatibility with the kernel's interrupt registration mechanisms.