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Date:   Wed, 24 Jul 2019 11:45:10 -0700
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Subject: [PATCH 1/3] Fix backward-ring-buffer.c format-truncation error
From:   Numfor Mbiziwo-Tiapo <nums@google.com>
To:     peterz@infradead.org, mingo@redhat.com, acme@kernel.org,
        alexander.shishkin@linux.intel.com, jolsa@redhat.com,
        namhyung@kernel.org, songliubraving@fb.com, mbd@fb.com
Cc:     linux-kernel@vger.kernel.org, irogers@google.com,
        eranian@google.com, Numfor Mbiziwo-Tiapo <nums@google.com>
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Perf does not build with the ubsan (undefined behavior sanitizer)
and there is an error that says:

tests/backward-ring-buffer.c:23:45: error: =E2=80=98%d=E2=80=99 directive o=
utput
may be truncated writing between 1 and 10 bytes into a region of
size 8 [-Werror=3Dformat-truncation=3D]
   snprintf(proc_name, sizeof(proc_name), "p:%d\n", i);

This can be reproduced by running (from the tip directory):
make -C tools/perf USE_CLANG=3D1 EXTRA_CFLAGS=3D"-fsanitize=3Dundefined"

Th error occurs because they are writing to the 10 byte buffer - the
index 'i' of the for loop and the 2 byte hardcoded string. If somehow 'i'
was greater than 8 bytes (10 - 2), then the snprintf function would
truncate the string. Increasing the size of the buffer fixes the error.

Signed-off-by: Numfor Mbiziwo-Tiapo <nums@google.com>
---
 tools/perf/tests/backward-ring-buffer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/tests/backward-ring-buffer.c b/tools/perf/tests/bac=
kward-ring-buffer.c
index 6d598cc071ae..1a9c3becf5ff 100644
--- a/tools/perf/tests/backward-ring-buffer.c
+++ b/tools/perf/tests/backward-ring-buffer.c
@@ -18,7 +18,7 @@ static void testcase(void)
 	int i;
=20
 	for (i =3D 0; i < NR_ITERS; i++) {
-		char proc_name[10];
+		char proc_name[15];
=20
 		snprintf(proc_name, sizeof(proc_name), "p:%d\n", i);
 		prctl(PR_SET_NAME, proc_name);
--=20
2.22.0.657.g960e92d24f-goog