CVE-2026-90002

Summary

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

ftrace: Take trace_array reference before accessing its ftrace_ops

The trace instance files set_ftrace_filter and set_ftrace_notrace was updated to work with specific trace instances (trace_arrays). The issue is that when these files are opened, there is a small race window where it will use the ftrace_ops from the inode->private pointer to get a reference to the trace_array and then take its reference. The problem is that the ftrace_ops itself could be freed. If the rmdir on the instance happens at the same time the set_ftrace_filter file is opened, the rmdir could have also freed the ftrace_ops and referencing it will cause a use-after-free bug and crash the kernel.

Instead, pass in the trace_array as the file private data (NULL for the top level instance), and then pass both the trace_array and the ftrace_ops to the ftrace_regex_open() function. If the trace_array is NULL, then it just uses the ftrace_ops without the need to take its reference (like normal). If the ftrace_ops is NULL, that is only the case for the top level instance and the global_ops can be used.

This allows the trace_array to have its reference incremented before touching the ftrace_ops that could also be freed when the instance is.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/83fd7eca5ab0d3ac3f23bff889175d847e21af06
• https://git.kernel.org/stable/c/cee8f286794df916553d8d445eac5c323ec5b0f8
• https://git.kernel.org/stable/c/9100191e5acb2e5ea2313f436667bb5fce129f47

• ←Previous
• Next→