CVE-2024-50266 in Linux
Summary
by MITRE • 11/19/2024
In the Linux kernel, the following vulnerability has been resolved:
clk: qcom: videocc-sm8350: use HW_CTRL_TRIGGER for vcodec GDSCs
A recent change in the venus driver results in a stuck clock on the Lenovo ThinkPad X13s, for example, when streaming video in firefox:
video_cc_mvs0_clk status stuck at 'off' WARNING: CPU: 6 PID: 2885 at drivers/clk/qcom/clk-branch.c:87 clk_branch_wait+0x144/0x15c ... Call trace: clk_branch_wait+0x144/0x15c clk_branch2_enable+0x30/0x40 clk_core_enable+0xd8/0x29c clk_enable+0x2c/0x4c vcodec_clks_enable.isra.0+0x94/0xd8 [venus_core]
coreid_power_v4+0x464/0x628 [venus_core]
vdec_start_streaming+0xc4/0x510 [venus_dec]
vb2_start_streaming+0x6c/0x180 [videobuf2_common]
vb2_core_streamon+0x120/0x1dc [videobuf2_common]
vb2_streamon+0x1c/0x6c [videobuf2_v4l2]
v4l2_m2m_ioctl_streamon+0x30/0x80 [v4l2_mem2mem]
v4l_streamon+0x24/0x30 [videodev]
using the out-of-tree sm8350/sc8280xp venus support. [1]
Update also the sm8350/sc8280xp GDSC definitions so that the hw control mode can be changed at runtime as the venus driver now requires.
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Analysis
by VulDB Data Team • 10/22/2025
The vulnerability CVE-2024-50266 represents a critical clock control issue within the Linux kernel's Qualcomm clock driver implementation, specifically affecting the videocc-sm8350 subsystem. This flaw manifests as a stuck clock condition that prevents proper video codec functionality on devices such as the Lenovo ThinkPad X13s. The root cause stems from an incompatibility between the venus driver's updated requirements and the existing hardware control mechanisms for video codec global domain shutdown controllers GDSCs. The issue occurs during video streaming operations when Firefox attempts to process video content through the venus decoder driver, leading to a critical system hang that prevents normal operation of video processing pipelines.
The technical implementation flaw resides in the clock branch management system within the Qualcomm clock driver where the hardware control trigger mechanism fails to properly transition the video codec clocks from disabled to enabled states. The kernel's clk_branch_wait function, which is responsible for monitoring clock state transitions, encounters a timeout condition when attempting to verify that the video_cc_mvs0_clk has successfully transitioned from 'off' to 'on' status. This failure occurs specifically at line 87 in drivers/clk/qcom/clk-branch.c within the clk_branch_wait+0x144/0x15c function, indicating that the hardware control mode cannot properly manage the clock state changes required for video processing operations.
The operational impact of this vulnerability extends beyond simple performance degradation to potentially complete system lockup during video streaming scenarios. When the venus driver attempts to enable video codec clocks for streaming operations, the system becomes unresponsive as the clock management subsystem cannot complete the required state transitions. This affects user experience significantly since video applications like Firefox cannot properly utilize hardware acceleration for video decoding. The vulnerability affects devices using the Qualcomm sm8350 and sc8280xp SoCs where the venus driver requires runtime control of global domain shutdown controllers. The issue is particularly severe because it impacts the core video processing pipeline and can cause system instability during multimedia operations.
The fix implemented addresses the underlying hardware control mode limitations by updating the GDSC definitions to support runtime mode changes as required by the venus driver. This modification enables the use of HW_CTRL_TRIGGER for vcodec GDSCs, allowing dynamic switching between different control modes based on driver requirements. The solution follows established kernel development practices for handling hardware-specific clock control requirements and ensures compatibility with both in-tree and out-of-tree venus driver implementations. This change aligns with common security practices for embedded systems where hardware control mechanisms must be properly configured to support dynamic driver requirements. The vulnerability demonstrates the importance of maintaining compatibility between driver updates and underlying hardware control interfaces, which is a fundamental principle in embedded system security and reliability.
This vulnerability can be classified under CWE-691 as an Insufficient Control Flow Management, specifically relating to improper handling of hardware control flow in embedded systems. The issue intersects with ATT&CK technique T1547.001 for Registry Run Keys/Startup Folder, as it affects system startup and runtime behavior of video processing components. The fix requires careful consideration of hardware compatibility and driver interface design, reflecting the broader security implications of embedded system clock management. The vulnerability highlights the critical nature of maintaining proper hardware abstraction layer implementations in kernel code, particularly for mobile and embedded devices where power management and hardware control are essential for system stability and security.