CVE-2022-50226

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

crypto: ccp - Use kzalloc for sev ioctl interfaces to prevent kernel memory leak

For some sev ioctl interfaces, input may be passed that is less than or equal to SEV_FW_BLOB_MAX_SIZE, but larger than the data that PSP firmware returns. In this case, kmalloc will allocate memory that is the size of the input rather than the size of the data. Since PSP firmware doesnt fully overwrite the buffer, the sev ioctl interfaces with the issue may return uninitialized slab memory.

Currently, all of the ioctl interfaces in the ccp driver are safe, but to prevent future problems, change all ioctl interfaces that allocate memory with kmalloc to use kzalloc and memset the data buffer to zero in sev_ioctl_do_platform_status.

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/13dc15a3f5fd7f884e4bfa8c011a0ae868df12ae
• https://git.kernel.org/stable/c/4c5300f6f5e18b11c02a92f136e69b98fddba15e
• https://git.kernel.org/stable/c/caa395aa16e7c9193fd7fa6cde462dd8229d4953
• https://git.kernel.org/stable/c/e11fb0a3a39bb42da35fa662c46ce7391f277436
• https://git.kernel.org/stable/c/f2a920daa780956b987c14b9f23de7c3c8915bf2