CVE-2022-50466

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

fs/binfmt_elf: Fix memory leak in load_elf_binary()

There is a memory leak reported by kmemleak:

unreferenced object 0xffff88817104ef80 (size 224): comm xfs_admin, pid 47165, jiffies 4298708825 (age 1333.476s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ……………. 60 a8 b3 00 81 88 ff ff a8 10 5a 00 81 88 ff ff `………Z….. backtrace: [] __alloc_file+0x21/0x250 [] alloc_empty_file+0x41/0xf0 [] path_openat+0xea/0x3d30 [] do_filp_open+0x1b9/0x290 [] do_open_execat+0xce/0x5b0 [] open_exec+0x27/0x50 [] load_elf_binary+0x510/0x3ed0 [] bprm_execve+0x599/0x1240 [] do_execveat_common.isra.0+0x4c7/0x680 [] __x64_sys_execve+0x88/0xb0 [] do_syscall_64+0x35/0x80

If interp_elf_ex fails to allocate memory in load_elf_binary(), the program will take the out_free_ph error handing path, resulting in interpreter file resource is not released.

Fix it by adding an error handing path out_free_file, which will release the file resource when interp_elf_ex failed to allocate memory.

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/265b6fb780f57d10449a40e94219b28fa52479cc
• https://git.kernel.org/stable/c/594d2a14f2168c09b13b114c3d457aa939403e52
• https://git.kernel.org/stable/c/706215300411d48db6b51a5832b872632a84bbc1
• https://git.kernel.org/stable/c/acd9b4914f1c5928c7ae8ebc623d6291eb1a573a