CVE-2024-57934: 
Linux Kernel vulnerability analysis and mitigation

A race condition vulnerability was discovered in the Linux kernel's function graph tracer (CVE-2024-57934). The issue exists in the __ftrace_return_to_handler() function where a loop iterates over fgraph_array[] elements. The vulnerability was disclosed on January 21, 2025, affecting Linux kernel versions from 6.11 up to (excluding) 6.12.9, and version 6.13 release candidates (rc1-rc5) (NVD).

The vulnerability occurs when the compiler reloads fgraph_array[] after checking if an element is a fgraph_stub. This can race with an update to fgraph_array[] that introduces a fgraph_stub, potentially leading to processing of the stub which contains a null 'func_hash' field. This results in a NULL pointer dereference. The issue has been assigned a CVSS v3.1 base score of 4.7 (MEDIUM) with vector string CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H (NVD).

If successfully exploited, the vulnerability can lead to a NULL pointer dereference, potentially causing a system crash or denial of service condition. The impact is limited to local systems and requires low privileges to exploit (NVD).

The vulnerability has been fixed by adding READ_ONCE() when accessing fgraph_array[] to ensure that the gops compared against the fgraph_stub matches the gops processed later. The fix has been implemented in the Linux kernel through patches (Kernel Patch, Upstream Patch).