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 requires local access and high complexity to exploit. An attacker needs low privileges but no user interaction to trigger the vulnerability. The attack complexity is considered high due to the specific timing requirements needed to trigger the race condition (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).