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Commit 6bc6c77c authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Steven Rostedt (VMware)
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tracing/kprobes: Fix within_notrace_func() to check only notrace functions 

Fix within_notrace_func() to check only notrace functions and to ignore the
kprobe-event which can not solve symbol addresses.

within_notrace_func() returns true if the given kprobe events probe point
seems to be out-of-range. But that is not the correct place to check for it,
it should be done in kprobes afterwards.

kprobe-events allow users to define a probe point on "currently unloaded
module" so that it can trace the event during module load. In this case, the
user will put a probe on a symbol which is not in kallsyms yet and it hits
the within_notrace_func().  As a result, kprobe-events always refuses if
user defines a probe on a "currenly unloaded module".

Fixes: commit 45408c4f ("tracing: kprobes: Prohibit probing on notrace function")
Link: http://lkml.kernel.org/r/153319624799.29007.13604430345640129926.stgit@devbox



Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 44ec3ec0

kernel/trace/trace_kprobe.c

+5 −3
Original line number Diff line number Diff line
@@ -88,6 +88,7 @@ static nokprobe_inline unsigned long trace_kprobe_nhit(struct trace_kprobe *tk) 
	return nhit;

}



/* Return 0 if it fails to find the symbol address */

static nokprobe_inline

unsigned long trace_kprobe_address(struct trace_kprobe *tk)

{
@@ -96,6 +97,7 @@ unsigned long trace_kprobe_address(struct trace_kprobe *tk) 
	if (tk->symbol) {

		addr = (unsigned long)

			kallsyms_lookup_name(trace_kprobe_symbol(tk));

		if (addr)

			addr += tk->rp.kp.offset;

	} else {

		addr = (unsigned long)tk->rp.kp.addr;
@@ -519,8 +521,8 @@ static bool within_notrace_func(struct trace_kprobe *tk) 
	unsigned long offset, size, addr;



	addr = trace_kprobe_address(tk);

	if (!kallsyms_lookup_size_offset(addr, &size, &offset))

		return true;	/* Out of range. */

	if (!addr || !kallsyms_lookup_size_offset(addr, &size, &offset))

		return false;



	return !ftrace_location_range(addr - offset, addr - offset + size);

}