From 6bc6c77cfc6747292d5865d124cc31333b1b8536 Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Thu, 2 Aug 2018 16:50:48 +0900 Subject: [PATCH] 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 45408c4f9250 ("tracing: kprobes: Prohibit probing on notrace function") Link: http://lkml.kernel.org/r/153319624799.29007.13604430345640129926.stgit@devbox Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace_kprobe.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index deeb03ae21e1..2e13f77b9a37 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -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) { @@ -96,7 +97,8 @@ unsigned long trace_kprobe_address(struct trace_kprobe *tk) if (tk->symbol) { addr = (unsigned long) kallsyms_lookup_name(trace_kprobe_symbol(tk)); - addr += tk->rp.kp.offset; + 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); }