CVE-2023-53396

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

ubifs: Fix memory leak in do_rename

If renaming a file in an encrypted directory, function fscrypt_setup_filename allocates memory for a file name. This name is never used, and before returning to the caller the memory for it is not freed.

When running kmemleak on it we see that it is registered as a leak. The report below is triggered by a simple program rename that renames a file in an encrypted directory:

unreferenced object 0xffff888101502840 (size 32): comm rename, pid 9404, jiffies 4302582475 (age 435.735s) backtrace: __kmem_cache_alloc_node __kmalloc fscrypt_setup_filename do_rename ubifs_rename vfs_rename do_renameat2

To fix this we can remove the call to fscrypt_setup_filename as its not needed.

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/3a36d20e012903f45714df2731261fdefac900cb
• https://git.kernel.org/stable/c/43b2f7d690697182beed6f71aa57b7249d3cfc9c
• https://git.kernel.org/stable/c/517ddc0259d7a7231486bdafde8035c478bc4088
• https://git.kernel.org/stable/c/7e264f67b7d6580eff5c2696961039fd05c69258
• https://git.kernel.org/stable/c/9f565752b328fe53c9e42b7d4e4d89a1da63d738