[PATCH 2/3] Fix ordered-events.c array-bounds error

From: Numfor Mbiziwo-Tiapo
Date: Wed Jul 24 2019 - 14:45:30 EST

Perf does not build with the ubsan (undefined behavior sanitizer)
and there is an error that says:

error: array subscript is above array bounds [-Werror=array-bounds]
eprintf_time(n, var, t, fmt, ##__VA_ARGS__)

note: in expansion of macro âpr_time_Nâ
#define pr_oe_time(t, fmt, ...) pr_time_N(1, debug_ordered_events,
t, pr_fmt(fmt), ##__VA_ARGS__)

util/ordered-events.c:329:2: note: in expansion of macro âpr_oe_timeâ
pr_oe_time(oe->next_flush, "next_flush - ordered_events__flush
POST %s, nr_events %u\n",

This can be reproduced by running (from the tip directory):
make -C tools/perf USE_CLANG=1 EXTRA_CFLAGS="-fsanitize=undefined"

The error stems from the 'str' array in the __ordered_events__flush
function in tools/perf/util/ordered-events.c. On line 319 of this
file, they use values of the variable 'how' (which has the type enum
oeflush - defined in ordered-events.h) as indices for the 'str' array.
Since 'how' has 5 values and the 'str' array only has 3, when the 4th
and 5th values of 'how' (OE_FLUSH__TOP and OE_FLUSH__TIME) are used as
indices, this will go out of the bounds of the 'str' array.
Adding the matching strings from the enum values into the 'str' array
fixes this.

Signed-off-by: Numfor Mbiziwo-Tiapo <nums@xxxxxxxxxx>
tools/perf/util/ordered-events.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/tools/perf/util/ordered-events.c b/tools/perf/util/ordered-events.c
index 897589507d97..c092b0c39d2b 100644
--- a/tools/perf/util/ordered-events.c
+++ b/tools/perf/util/ordered-events.c
@@ -270,6 +270,8 @@ static int __ordered_events__flush(struct ordered_events *oe, enum oe_flush how,
"HALF ",
+ "TOP",
+ "TIME",
int err;
bool show_progress = false;