CVE-2022-49661

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

can: gs_usb: gs_usb_open/close(): fix memory leak

The gs_usb driver appears to suffer from a malady common to many USB CAN adapter drivers in that it performs usb_alloc_coherent() to allocate a number of USB request blocks (URBs) for RX, and then later relies on usb_kill_anchored_urbs() to free them, but this doesnt actually free them. As a result, this may be leaking DMA memory thats been used by the driver.

This commit is an adaptation of the techniques found in the esd_usb2 driver where a similar design pattern led to a memory leak. It explicitly frees the RX URBs and their DMA memory via a call to usb_free_coherent(). Since the RX URBs were allocated in the gs_can_open(), we remove them in gs_can_close() rather than in the disconnect function as was done in esd_usb2.

For more information, see the 928150fad41b (can: esd_usb2: fix memory leak).

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/0e60230bc64355c80abe993d1719fdb318094e20
• https://git.kernel.org/stable/c/2bda24ef95c0311ab93bda00db40486acf30bd0a
• https://git.kernel.org/stable/c/339fa9f80d3b94177a7a459c6d115d3b56007d5a
• https://git.kernel.org/stable/c/6f655b5e13fa4b27e915b6c209ac0da74fd75963
• https://git.kernel.org/stable/c/c1d806bc29ff7ffe0e2a023583c8720ed96cb0b0
• https://git.kernel.org/stable/c/d0b8e223998866b3e7b2895927d4e9689b0a80d8
• https://git.kernel.org/stable/c/d91492638b054f4a359621ef216242be5973ed6b
• https://git.kernel.org/stable/c/ffb6cc6601ec7c8fa963dcf76025df4a02f2cf5c