CVE-2023-53276

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

ubifs: Free memory for tmpfile name

When opening a ubifs tmpfile on an encrypted directory, function fscrypt_setup_filename allocates memory for the name that is to be stored in the directory entry, but after the name has been copied to the directory entry inode, the memory 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 tmpfile just opening a tmpfile:

unreferenced object 0xffff88810178f380 (size 32): comm tmpfile, pid 509, jiffies 4294934744 (age 1524.742s) backtrace: __kmem_cache_alloc_node __kmalloc fscrypt_setup_filename ubifs_tmpfile vfs_tmpfile path_openat

Free this memory after it has been copied to the inode.

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/107d481642c356a5668058066360fc473911e628
• https://git.kernel.org/stable/c/1e43d4284bdc3bd34bd770fea13910ac37ab0618
• https://git.kernel.org/stable/c/1fb815b38bb31d6af9bd0540b8652a0d6fe6cfd3
• https://git.kernel.org/stable/c/29738e1bcc799dd754711d4e4aab967f0c018175
• https://git.kernel.org/stable/c/823f554747f8aafaa965fb2f3ae794110ed429ef
• https://git.kernel.org/stable/c/8ad8c67a897e68426e85990ebfe0a7d1f71fc79f
• https://git.kernel.org/stable/c/b8f444a4fadfb5070ed7e298e0a5ceb4a18014f3
• https://git.kernel.org/stable/c/ce840284929b75dbbf062e0ce7fcb78a63b08b5e
• https://git.kernel.org/stable/c/fd197308c0e4f738c7ea687d5332035c5753881c