CVE-2023-53200

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

netfilter: x_tables: fix percpu counter block leak on error path when creating new netns

Here is the stack where we allocate percpu counter block:

+-< __alloc_percpu +-< xt_percpu_counter_alloc +-< find_check_entry # {arp,ip,ip6}_tables.c +-< translate_table

And it can be leaked on this code path:

+-> ip6t_register_table +-> translate_table # allocates percpu counter block +-> xt_register_table # fails

there is no freeing of the counter block on xt_register_table fail. Note: xt_percpu_counter_free should be called to free it like we do in do_replace through cleanup_entry helper (or in __ip6t_unregister_table).

Probability of hitting this error path is low AFAICS (xt_register_table can only return ENOMEM here, as it is not replacing anything, as we are creating new netns, and it is hard to imagine that all previous allocations succeeded and after that one in xt_register_table failed). But its worth fixing even the rare leak.

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/0af8c09c896810879387decfba8c942994bb61f5
• https://git.kernel.org/stable/c/3cc9610a87b7dde82f7360dd4eb6c2c27940ed57
• https://git.kernel.org/stable/c/512b6c4b83c91d007301ea7d7f095d16c3aceacd
• https://git.kernel.org/stable/c/e306dbee4c98025a9326386023a12ef4d887e9d1