CVE-2021-0257

On Juniper Networks MX Series and EX9200 Series platforms with Trio-based MPCs (Modular Port Concentrators) where Integrated Routing and Bridging (IRB) interfaces are configured and mapped to a VPLS instance or a Bridge-Domain, certain Layer 2 network events at Customer Edge (CE) devices may cause memory leaks in the MPC of Provider Edge (PE) devices which can cause an out of memory condition and MPC restart. When this issue occurs, there will be temporary traffic interruption until the MPC is restored. An administrator can use the following CLI command to monitor the status of memory usage level of the MPC: user@device> show system resource-monitor fpc FPC Resource Usage Summary Free Heap Mem Watermark : 20 % Free NH Mem Watermark : 20 % Free Filter Mem Watermark : 20 % * - Watermark reached Slot # % Heap Free RTT Average RTT 1 87 PFE # % ENCAP mem Free % NH mem Free % FW mem Free 0 NA 88 99 1 NA 89 99 When the issue is occurring, the value of “% NH mem Free” will go down until the MPC restarts. This issue affects MX Series and EX9200 Series with Trio-based PFEs (Packet Forwarding Engines), including MX-MPC1-3D, MX-MPC1E-3D, MX-MPC2-3D, MX-MPC2E-3D, MPC-3D-16XGE, and CHAS-MXxx Series MPCs. No other products or platforms are affected by this issue. This issue affects Juniper Networks Junos OS on MX Series, EX9200 Series: 17.3 versions prior to 17.3R3-S10; 17.4 versions prior to 17.4R3-S3; 18.2 versions prior to 18.2R3-S7; 18.3 versions prior to 18.3R3-S4; 18.4 versions prior to 18.4R3-S6; 19.2 versions prior to 19.2R3-S2; 19.3 versions prior to 19.3R3-S1; 19.4 versions prior to 19.4R2-S2, 19.4R3; 20.2 versions prior to 20.2R1-S3, 20.2R2; 20.3 versions prior to 20.3R1-S1,, 20.3R2. This issue does not affect Juniper Networks Junos OS: 17.3 versions prior to 17.3R3-S8; 17.4 versions prior to 17.4R3-S2; 18.1; 18.2 versions prior to 18.2R3-S4; 18.3 versions prior to 18.3R3-S2; 18.4 versions prior to 18.4R3-S1; 19.1; 19.2 versions prior to 19.2R2; 19.3 versions prior to 19.3R3; 19.4 versions prior to 19.4R2.

Weakness

The product does not sufficiently track and release allocated memory after it has been used, which slowly consumes remaining memory.

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://kb.juniper.net/JSA11148