CVE-2021-47516

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

nfp: Fix memory leak in nfp_cpp_area_cache_add()

In line 800 (#1), nfp_cpp_area_alloc() allocates and initializes a CPP area structure. But in line 807 (#2), when the cache is allocated failed, this CPP area structure is not freed, which will result in memory leak.

We can fix it by freeing the CPP area when the cache is allocated failed (#2).

792 int nfp_cpp_area_cache_add(struct nfp_cpp *cpp, size_t size) 793 { 794 struct nfp_cpp_area_cache *cache; 795 struct nfp_cpp_area *area;

800 area = nfp_cpp_area_alloc(cpp, NFP_CPP_ID(7, NFP_CPP_ACTION_RW, 0), 801 0, size); // #1: allocates and initializes

802 if (!area) 803 return -ENOMEM;

805 cache = kzalloc(sizeof(*cache), GFP_KERNEL); 806 if (!cache) 807 return -ENOMEM; // #2: missing free

817 return 0; 818 }

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/2e0e072e62fdaf7816220af08e05c020f0fcb77a
• https://git.kernel.org/stable/c/3e93abcdcec0436fbf0b6a88ae806902426895a2
• https://git.kernel.org/stable/c/484069b5de9d223cc1c64c6f80389a99cfef51f1
• https://git.kernel.org/stable/c/c56c96303e9289cc34716b1179597b6f470833de
• https://git.kernel.org/stable/c/eb51f639ef3fd5498b7def290ed8681b6aadd9a7
• https://git.kernel.org/stable/c/f707820c09239d6f67699d9b2ff57863cc7905b0