CVE-2026-90002ftrace: Take trace_array reference before accessing its ftrace_ops

Official description

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 packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/0124b36a7eac1dd0402146fc6c1f732877b9cd9f
• https://git.kernel.org/stable/c/ffe16fe221e25cd1915602e6753c3d3285ed9a98
• https://git.kernel.org/stable/c/8f062a6bfeb4b4e18d469a673aec23a7b73c3e8a
• https://git.kernel.org/stable/c/29266da8ee1d9be656b1f22460c49538e1930658
• https://git.kernel.org/stable/c/177cd8966325f0ffffa3c9381f9e0422019a3973
• https://git.kernel.org/stable/c/83fd7eca5ab0d3ac3f23bff889175d847e21af06
• https://git.kernel.org/stable/c/cee8f286794df916553d8d445eac5c323ec5b0f8
• https://git.kernel.org/stable/c/9100191e5acb2e5ea2313f436667bb5fce129f47