CVE-2022-49210

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

MIPS: pgalloc: fix memory leak caused by pgd_free()

pgd page is freed by generic implementation pgd_free() since commit f9cb654cb550 (asm-generic: pgalloc: provide generic pgd_free()), however, there are scenarios that the system uses more than one page as the pgd table, in such cases the generic implementation pgd_free() wont be applicable anymore. For example, when PAGE_SIZE_4KB is enabled and MIPS_VA_BITS_48 is not enabled in a 64bit system, the macro PGD_ORDER will be set as 1, which will cause allocating two pages as the pgd table. Well, at the same time, the generic implementation pgd_free() just free one pgd page, which will result in the memory leak.

The memory leak can be easily detected by executing shell command: while true; do ls > /dev/null; grep MemFree /proc/meminfo; done

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/1bf0d78c8cc3cf615a6e7bf33ada70b73592f0a1
• https://git.kernel.org/stable/c/2bc5bab9a763d520937e4f3fe8df51c6a1eceb97
• https://git.kernel.org/stable/c/5a8501d34b261906e4c76ec9da679f2cb4d309ed
• https://git.kernel.org/stable/c/d29cda15cab086d82d692de016f7249545d4b6b4
• https://git.kernel.org/stable/c/fa3d44424579972cc7c4fac3d9cf227798ebdfa0