CVE-2021-47537

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

octeontx2-af: Fix a memleak bug in rvu_mbox_init()

In rvu_mbox_init(), mbox_regions is not freed or passed out under the switch-default region, which could lead to a memory leak.

Fix this bug by changing return err to goto free_regions.

This bug was found by a static analyzer. The analysis employs differential checking to identify inconsistent security operations (e.g., checks or kfrees) between two code paths and confirms that the inconsistent operations are not recovered in the current function or the callers, so they constitute bugs.

Note that, as a bug found by static analysis, it can be a false positive or hard to trigger. Multiple researchers have cross-reviewed the bug.

Builds with CONFIG_OCTEONTX2_AF=y show no new warnings, and our static analyzer no longer warns about this code.

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/1c0ddef45b7e3dbe3ed073695d20faa572b7056a
• https://git.kernel.org/stable/c/e07a097b4986afb8f925d0bb32612e1d3e88ce15
• https://git.kernel.org/stable/c/1c0ddef45b7e3dbe3ed073695d20faa572b7056a
• https://git.kernel.org/stable/c/e07a097b4986afb8f925d0bb32612e1d3e88ce15