CVE-2023-52494 - Linux Kernel Vulnerability Resolved: MHI Host Event Ring Read Pointer Alignment Check

In the Linux kernel, a vulnerability has been recently resolved that affects the event ring read pointer and could lead to multiple issues like Denial of Service (DoS) or ring buffer memory corruption. This post will dive into the details of this vulnerability, known as CVE-2023-52494, and the steps taken to address it.

Problem

The Linux kernel utilizes an event ring read pointer to manage and keep track of events in a buffer range. The original code checks the read pointer with the "is_valid_ring_ptr" function to ensure that it falls within the correct buffer range. However, this check is insufficient, as the pointer may still be unaligned, which can lead to various issues, including DoS or ring buffer memory corruption. The vulnerability is present in the bus: mhi: host segment of the Linux kernel.

Solution

To mitigate the risks associated with this vulnerability, the Linux kernel has introduced an alignment check for the event ring read pointer. This alignment check ensures that the pointer is aligned with 128-bit (struct mhi_ring_element) boundary, significantly reducing the risk of DoS or ring buffer memory corruption. The updated code snippet is provided below for reference:

static bool is_valid_ring_ptr(struct mhi_ring *ring, void *ptr)
{
    return ptr >= ring->base && ptr < ring->base + ring->len &&
            IS_ALIGNED((uintptr_t)ptr, sizeof(struct mhi_ring_element));
}

In this updated function, the addition of the IS_ALIGNED((uintptr_t)ptr, sizeof(struct mhi_ring_element)) check ensures that the pointer's alignment is correct.

Original References

The original patch and discussion regarding this vulnerability can be found on the Linux Kernel Mailing List (LKML) at the following link:

https://lkml.org/lkml/2022/11/16/146

Additionally, the official commit for this change can be found in the Linux Kernel source code repository at:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=772f97d8e2d4881d

Exploit Details

As of now, no known exploits have been found in the wild targeting this specific vulnerability. However, due to the potential impact that this vulnerability could have on systems running affected versions of the Linux kernel, it is highly recommended that users update their kernel to the latest version to secure their systems effectively.

Conclusion

CVE-2023-52494 is a notable Linux kernel vulnerability that has been resolved by including an alignment check for the event ring read pointer. Ensuring that the pointer is properly aligned helps prevent DoS attacks or ring buffer memory corruption. Users are encouraged to update their Linux kernel to the latest version to apply this patch and protect their systems from potential exploitation.

Timeline

Published on: 03/11/2024 18:15:17 UTC
Last modified on: 03/12/2024 12:40:13 UTC