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Commit 784c2eb3 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Greg Kroah-Hartman
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tracing/kprobes: Check the probe on unloaded module correctly 

[ Upstream commit 59158ec4aef7d44be51a6f3e7e17fc64c32604eb ]

Current kprobe event doesn't checks correctly whether the
given event is on unloaded module or not. It just checks
the event has ":" in the name.

That is not enough because if we define a probe on non-exist
symbol on loaded module, it allows to define that (with
warning message)

To ensure it correctly, this searches the module name on
loaded module list and only if there is not, it allows to
define it. (this event will be available when the target
module is loaded)

Link: http://lkml.kernel.org/r/153547309528.26502.8300278470528281328.stgit@devbox



Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 7ecd146b

kernel/trace/trace_kprobe.c

+26 −13
Original line number Diff line number Diff line
@@ -61,9 +61,23 @@ static nokprobe_inline bool trace_kprobe_within_module(struct trace_kprobe *tk, 
	return strncmp(mod->name, name, len) == 0 && name[len] == ':';

}



static nokprobe_inline bool trace_kprobe_is_on_module(struct trace_kprobe *tk)

static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk)

{

	return !!strchr(trace_kprobe_symbol(tk), ':');

	char *p;

	bool ret;



	if (!tk->symbol)

		return false;

	p = strchr(tk->symbol, ':');

	if (!p)

		return true;

	*p = '\0';

	mutex_lock(&module_mutex);

	ret = !!find_module(tk->symbol);

	mutex_unlock(&module_mutex);

	*p = ':';



	return ret;

}



static nokprobe_inline unsigned long trace_kprobe_nhit(struct trace_kprobe *tk)
@@ -554,19 +568,13 @@ static int __register_trace_kprobe(struct trace_kprobe *tk) 
	else

		ret = register_kprobe(&tk->rp.kp);



	if (ret == 0)

	if (ret == 0) {

		tk->tp.flags |= TP_FLAG_REGISTERED;

	else {

		if (ret == -ENOENT && trace_kprobe_is_on_module(tk)) {

			pr_warn("This probe might be able to register after target module is loaded. Continue.\n");

			ret = 0;

	} else if (ret == -EILSEQ) {

		pr_warn("Probing address(0x%p) is not an instruction boundary.\n",

			tk->rp.kp.addr);

		ret = -EINVAL;

	}

	}



	return ret;

}
@@ -629,6 +637,11 @@ static int register_trace_kprobe(struct trace_kprobe *tk) 


	/* Register k*probe */

	ret = __register_trace_kprobe(tk);

	if (ret == -ENOENT && !trace_kprobe_module_exist(tk)) {

		pr_warn("This probe might be able to register after target module is loaded. Continue.\n");

		ret = 0;

	}



	if (ret < 0)

		unregister_kprobe_event(tk);

	else