From: Jiri Olsa jolsa@kernel.org
commit 5f81018753dfd4989e33ece1f0cb6b8aae498b82 upstream.
While running bpf selftests it's possible to get following fault:
general protection fault, probably for non-canonical address \ 0x6b6b6b6b6b6b6b6b: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI ... Call Trace: <TASK> fprobe_handler+0xc1/0x270 ? __pfx_bpf_testmod_init+0x10/0x10 ? __pfx_bpf_testmod_init+0x10/0x10 ? bpf_fentry_test1+0x5/0x10 ? bpf_fentry_test1+0x5/0x10 ? bpf_testmod_init+0x22/0x80 ? do_one_initcall+0x63/0x2e0 ? rcu_is_watching+0xd/0x40 ? kmalloc_trace+0xaf/0xc0 ? do_init_module+0x60/0x250 ? __do_sys_finit_module+0xac/0x120 ? do_syscall_64+0x37/0x90 ? entry_SYSCALL_64_after_hwframe+0x72/0xdc </TASK>
In unregister_fprobe function we can't release fp->rethook while it's possible there are some of its users still running on another cpu.
Moving rethook_free call after fp->ops is unregistered with unregister_ftrace_function call.
Link: https://lore.kernel.org/all/20230615115236.3476617-1-jolsa@kernel.org/
Fixes: 5b0ab78998e3 ("fprobe: Add exit_handler support") Cc: stable@vger.kernel.org Reviewed-by: Steven Rostedt (Google) rostedt@goodmis.org Signed-off-by: Jiri Olsa jolsa@kernel.org Acked-by: Masami Hiramatsu (Google) mhiramat@kernel.org Signed-off-by: Masami Hiramatsu (Google) mhiramat@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/trace/fprobe.c | 12 +++--------- 1 file changed, 3 insertions(+), 9 deletions(-)
--- a/kernel/trace/fprobe.c +++ b/kernel/trace/fprobe.c @@ -307,19 +307,13 @@ int unregister_fprobe(struct fprobe *fp) fp->ops.saved_func != fprobe_kprobe_handler)) return -EINVAL;
- /* - * rethook_free() starts disabling the rethook, but the rethook handlers - * may be running on other processors at this point. To make sure that all - * current running handlers are finished, call unregister_ftrace_function() - * after this. - */ - if (fp->rethook) - rethook_free(fp->rethook); - ret = unregister_ftrace_function(&fp->ops); if (ret < 0) return ret;
+ if (fp->rethook) + rethook_free(fp->rethook); + ftrace_free_filter(&fp->ops);
return ret;