[for-next][PATCH 25/34] tracing/kprobes: Fix within_notrace_func() to check only notrace functions

From: Steven Rostedt
Date: Sat Aug 11 2018 - 09:51:07 EST

From: Masami Hiramatsu <mhiramat@xxxxxxxxxx>

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 <mhiramat@xxxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
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)
- 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);