CVE-2021-47205

In the Linux kernel, the following vulnerability has been resolved:

clk: sunxi-ng: Unregister clocks/resets when unbinding

Currently, unbinding a CCU driver unmaps the devices MMIO region, while leaving its clocks/resets and their providers registered. This can cause a page fault later when some clock operation tries to perform MMIO. Fix this by separating the CCU initialization from the memory allocation, and then using a devres callback to unregister the clocks and resets.

This also fixes a memory leak of the struct ccu_reset, and uses the correct owner (the specific platform driver) for the clocks and resets.

Early OF clock providers are never unregistered, and limited error handling is possible, so they are mostly unchanged. The error reporting is made more consistent by moving the message inside of_sunxi_ccu_probe.

Weakness

The product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.

Affected Software

Potential Mitigations

• Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone.
• For example, glibc in Linux provides protection against free of invalid pointers.
• When using Xcode to target OS X or iOS, enable automatic reference counting (ARC) [REF-391].
• To help correctly and consistently manage memory when programming in C++, consider using a smart pointer class such as std::auto_ptr (defined by ISO/IEC ISO/IEC 14882:2003), std::shared_ptr and std::unique_ptr (specified by an upcoming revision of the C++ standard, informally referred to as C++ 1x), or equivalent solutions such as Boost.

References

• https://git.kernel.org/stable/c/9bec2b9c6134052994115d2d3374e96f2ccb9b9d
• https://git.kernel.org/stable/c/b5dd513daa70ee8f6d281a20bd28485ee9bb7db2
• https://git.kernel.org/stable/c/9bec2b9c6134052994115d2d3374e96f2ccb9b9d
• https://git.kernel.org/stable/c/b5dd513daa70ee8f6d281a20bd28485ee9bb7db2