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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>
Subject: [PATCH 3/3] Fix insn.c misaligned address error
Date: Wed, 24 Jul 2019 11:45:12 -0700	[thread overview]
Message-ID: <20190724184512.162887-4-nums@google.com> (raw)
In-Reply-To: <20190724184512.162887-1-nums@google.com>

The ubsan (undefined behavior sanitizer) version of perf throws an
error on the 'x86 instruction decoder - new instructions' function
of perf test.

To reproduce this run:
make -C tools/perf USE_CLANG=1 EXTRA_CFLAGS="-fsanitize=undefined"

then run: tools/perf/perf test 62 -v

The error occurs in the __get_next macro (line 34) where an int is
read from a potentially unaligned address. Using memcpy instead of
assignment from an unaligned pointer.

Signed-off-by: Numfor Mbiziwo-Tiapo <nums@google.com>
---
 tools/perf/util/intel-pt-decoder/insn.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/intel-pt-decoder/insn.c b/tools/perf/util/intel-pt-decoder/insn.c
index ca983e2bea8b..de1944c60aa9 100644
--- a/tools/perf/util/intel-pt-decoder/insn.c
+++ b/tools/perf/util/intel-pt-decoder/insn.c
@@ -31,7 +31,8 @@
 	((insn)->next_byte + sizeof(t) + n <= (insn)->end_kaddr)
 
 #define __get_next(t, insn)	\
-	({ t r = *(t*)insn->next_byte; insn->next_byte += sizeof(t); r; })
+	({ t r; memcpy(&r, insn->next_byte, sizeof(t)); \
+		insn->next_byte += sizeof(t); r; })
 
 #define __peek_nbyte_next(t, insn, n)	\
 	({ t r = *(t*)((insn)->next_byte + n); r; })
-- 
2.22.0.657.g960e92d24f-goog


  parent reply	other threads:[~2019-07-24 18:45 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-24 18:45 [PATCH 0/3] Perf UBsan Patches Numfor Mbiziwo-Tiapo
2019-07-24 18:45 ` [PATCH 1/3] Fix backward-ring-buffer.c format-truncation error Numfor Mbiziwo-Tiapo
2019-07-25 13:08   ` David Laight
2019-07-26 19:40   ` Arnaldo Carvalho de Melo
2019-07-29 20:57     ` [PATCH v2] Fix annotate.c use of uninitialized value error Numfor Mbiziwo-Tiapo
2019-08-07 11:32       ` Jiri Olsa
2019-10-25 22:11         ` Ian Rogers
2020-07-09  0:54           ` Ian Rogers
2020-07-09 15:38             ` Arnaldo Carvalho de Melo
2019-07-24 18:45 ` [PATCH 2/3] Fix ordered-events.c array-bounds error Numfor Mbiziwo-Tiapo
2019-07-26 19:33   ` Arnaldo Carvalho de Melo
2019-07-26 19:35   ` Arnaldo Carvalho de Melo
2019-07-24 18:45 ` Numfor Mbiziwo-Tiapo [this message]
2019-07-25 13:06   ` [PATCH 3/3] Fix insn.c misaligned address error David Laight
2019-07-25 21:18     ` Ian Rogers
2019-07-26 19:38   ` Arnaldo Carvalho de Melo
2019-07-27  9:46     ` Masami Hiramatsu
2019-07-29  8:22       ` Adrian Hunter
2019-07-29 19:32         ` Ian Rogers
2019-07-30  7:50           ` Adrian Hunter
2019-07-30  0:47         ` Masami Hiramatsu
2019-07-30  7:53           ` Adrian Hunter
2019-07-30  9:17             ` David Laight

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