CVE-2022-49549

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

x86/MCE/AMD: Fix memory leak when threshold_create_bank() fails

In mce_threshold_create_device(), if threshold_create_bank() fails, the previously allocated threshold banks array @bp will be leaked because the call to mce_threshold_remove_device() will not free it.

This happens because mce_threshold_remove_device() fetches the pointer through the threshold_banks per-CPU variable but bp is written there only after the bank creation is successful, and not before, when threshold_create_bank() fails.

Add a helper which unwinds all the bank creation work previously done and pass into it the previously allocated threshold banks array for freeing.

[ bp: Massage. ]

Weakness

The product does not sufficiently track and release allocated memory after it has been used, which slowly consumes remaining memory.

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/396b8e7ab2a99ddac57d3522b3da5e58cb608d37
• https://git.kernel.org/stable/c/9708f1956eeb70c86943e0bc62fa3b0101b59616
• https://git.kernel.org/stable/c/b4acb8e7f1594607bc9017ef0aacb40b24a003d6
• https://git.kernel.org/stable/c/cc0dd4456f9573bf8af9b4d8754433918e809e1e
• https://git.kernel.org/stable/c/e5f28623ceb103e13fc3d7bd45edf9818b227fd0