tracing: fprobe events: Fix possible UAF on modules

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: tracing: fprobe events: Fix possible UAF on modules Commit ac91052f0ae5 ("tracing: tprobe-events: Fix leakage of module refcount") moved try_module_get() from __find_tracepoint_module_cb() to find_tracepoint() caller, but that introduced a possible UAF because the module can be unloaded before try_module_get(). In this case, the module object should be freed too. Thus, try_module_get() does not only fail but may access to the freed object. To avoid that, try_module_get() in __find_tracepoint_module_cb() again.

References

• https://git.kernel.org/stable/c/868df4eb784c3ccc7e4340a9ea993cbbedca167e
• https://git.kernel.org/stable/c/a27d2de2472b1cc7d582ab405d1d5832a80481de
• https://git.kernel.org/stable/c/626f01f4d26e8cf92e69c1df53036153c8e98a20
• https://git.kernel.org/stable/c/dd941507a9486252d6fcf11814387666792020f3