[PATCH 2/4] perf probe: Ensure offset provided is not greater than function length

[Arnaldo Carvalho de Melo]

From: Prashanth Nageshappa <prashanth@xxxxxxxxxxxxxxxxxx>

The perf probe command allows kprobe to be inserted at any offset from a
function start, which results in adding kprobes to unintended location.

Example: perf probe do_fork+10000 is allowed even though size of do_fork
is ~904.

This patch will ensure probe addition fails when the offset specified is
greater than size of the function.

Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Cc: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>
Cc: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Jason Baron <jbaron@xxxxxxxxxx>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Link: http://lkml.kernel.org/r/4F473F33.4060409@xxxxxxxxxxxxxxxxxx
Signed-off-by: Prashanth Nageshappa <prashanth@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/util/probe-finder.c |   12 +++++++++++-
 1 files changed, 11 insertions(+), 1 deletions(-)

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 5d73262..74bd2e6 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -672,7 +672,7 @@ static int find_variable(Dwarf_Die *sc_die, struct probe_finder *pf)
 static int convert_to_trace_point(Dwarf_Die *sp_die, Dwarf_Addr paddr,
 				  bool retprobe, struct probe_trace_point *tp)
 {
-	Dwarf_Addr eaddr;
+	Dwarf_Addr eaddr, highaddr;
 	const char *name;
 
 	/* Copy the name of probe point */
@@ -683,6 +683,16 @@ static int convert_to_trace_point(Dwarf_Die *sp_die, Dwarf_Addr paddr,
 				   dwarf_diename(sp_die));
 			return -ENOENT;
 		}
+		if (dwarf_highpc(sp_die, &highaddr) != 0) {
+			pr_warning("Failed to get end address of %s\n",
+				   dwarf_diename(sp_die));
+			return -ENOENT;
+		}
+		if (paddr > highaddr) {
+			pr_warning("Offset specified is greater than size of %s\n",
+				   dwarf_diename(sp_die));
+			return -EINVAL;
+		}
 		tp->symbol = strdup(name);
 		if (tp->symbol == NULL)
 			return -ENOMEM;
-- 
1.7.9.123.g65da0

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