CVE-2021-47024

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

vsock/virtio: free queued packets when closing socket

As reported by syzbot [1], there is a memory leak while closing the socket. We partially solved this issue with commit ac03046ece2b (vsock/virtio: free packets during the socket release), but we forgot to drain the RX queue when the socket is definitely closed by the scheduled work.

To avoid future issues, lets use the new virtio_transport_remove_sock() to drain the RX queue before removing the socket from the af_vsock lists calling vsock_remove_sock().

[1] https://syzkaller.appspot.com/bug?extid=24452624fc4c571eedd9

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://git.kernel.org/stable/c/27691665145e74a45034a9dccf1150cf1894763a
• https://git.kernel.org/stable/c/37c38674ef2f8d7e8629e5d433c37d6c1273d16b
• https://git.kernel.org/stable/c/8432b8114957235f42e070a16118a7f750de9d39
• https://git.kernel.org/stable/c/b605673b523fe33abeafb2136759bcbc9c1e6ebf
• https://git.kernel.org/stable/c/27691665145e74a45034a9dccf1150cf1894763a
• https://git.kernel.org/stable/c/37c38674ef2f8d7e8629e5d433c37d6c1273d16b
• https://git.kernel.org/stable/c/8432b8114957235f42e070a16118a7f750de9d39
• https://git.kernel.org/stable/c/b605673b523fe33abeafb2136759bcbc9c1e6ebf