[PATCH] perf - ensure offset provided during probe addition is not greater than function length

[Prashanth Nageshappa <prashanth@linux.vnet.ibm.com>]

perf probe 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.


Signed-off-by: Prashanth Nageshappa <prashanth@linux.vnet.ibm.com>
---

 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..d298f94 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;