CVE-2024-56712: 
Linux Kernel vulnerability analysis and mitigation

A memory leak vulnerability was discovered in the Linux kernel's udmabuf driver (CVE-2024-56712). The issue occurs in the exportudmabuf() function when dmabuffd() fails due to a full FD table, resulting in a created dmabuf owning the udmabuf without proper cleanup, leading to a memory leak with a dangling pointer. The vulnerability affects Linux kernel versions from 4.20 up to 6.12.7, including release candidates 6.13-rc1 through 6.13-rc3 (NVD).

The vulnerability stems from improper error handling in udmabufcreate() where the function tears down the udmabuf without addressing the containing dmabuf when dmabuffd() fails. This results in a dma_buf remaining in memory with a dangling pointer. The issue has been present since the introduction of udmabuf. The vulnerability has been assigned a CVSS v3.1 base score of 5.5 (Medium) with the vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H, indicating local access requirements and high availability impact (NVD).

The primary impact of this vulnerability is a memory leak in the Linux kernel. While the dangling pointer doesn't appear to cause immediate severe consequences beyond the memory leak, it could potentially lead to system resource exhaustion over time (Kernel Patch).

The vulnerability has been fixed by moving the dmabuffd() call out of exportudmabuf() to implement different error handling. The fix ensures proper cleanup of both the dmabuf and ubuf through udmabufops.release when dmabuffd() fails (Kernel Patch).