linux-kernel - Re: [PATCH] perf test: Fix unaligned access in sample parsing test

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Date:   Thu, 18 Feb 2021 16:09:08 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Adrian Hunter <adrian.hunter@...el.com>
Cc:     Namhyung Kim <namhyung@...nel.org>, Jiri Olsa <jolsa@...hat.com>,
        Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Stephane Eranian <eranian@...gle.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Ian Rogers <irogers@...gle.com>
Subject: Re: [PATCH] perf test: Fix unaligned access in sample parsing test

Em Mon, Feb 15, 2021 at 08:26:08AM +0200, Adrian Hunter escreveu:
> On 14/02/21 11:16 am, Namhyung Kim wrote:
> > The ubsan reported the following error.  It was because sample's raw
> > data missed u32 padding at the end.  So it broke the alignment of the
> > array after it.
> > 
> > The raw data contains an u32 size prefix so the data size should have
> > an u32 padding after 8-byte aligned data.
> > 
> > 27: Sample parsing  :util/synthetic-events.c:1539:4:
> >   runtime error: store to misaligned address 0x62100006b9bc for type
> >   '__u64' (aka 'unsigned long long'), which requires 8 byte alignment
> > 0x62100006b9bc: note: pointer points here
> >   00 00 00 00 ff ff ff ff  ff ff ff ff ff ff ff ff  ff ff ff ff ff ff ff ff  ff ff ff ff ff ff ff ff
> >               ^
> >     #0 0x561532a9fc96 in perf_event__synthesize_sample util/synthetic-events.c:1539:13
> >     #1 0x5615327f4a4f in do_test tests/sample-parsing.c:284:8
> >     #2 0x5615327f3f50 in test__sample_parsing tests/sample-parsing.c:381:9
> >     #3 0x56153279d3a1 in run_test tests/builtin-test.c:424:9
> >     #4 0x56153279c836 in test_and_print tests/builtin-test.c:454:9
> >     #5 0x56153279b7eb in __cmd_test tests/builtin-test.c:675:4
> >     #6 0x56153279abf0 in cmd_test tests/builtin-test.c:821:9
> >     #7 0x56153264e796 in run_builtin perf.c:312:11
> >     #8 0x56153264cf03 in handle_internal_command perf.c:364:8
> >     #9 0x56153264e47d in run_argv perf.c:408:2
> >     #10 0x56153264c9a9 in main perf.c:538:3
> >     #11 0x7f137ab6fbbc in __libc_start_main (/lib64/libc.so.6+0x38bbc)
> >     #12 0x561532596828 in _start ...
> > 
> > SUMMARY: UndefinedBehaviorSanitizer: misaligned-pointer-use
> >  util/synthetic-events.c:1539:4 in

Thanks, applied.

- Arnaldo

 
> > Fixes: 045f8cd8542d ("perf tests: Add a sample parsing test")
> > Cc: Adrian Hunter <adrian.hunter@...el.com>
> > Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> 
> Acked-by: Adrian Hunter <adrian.hunter@...el.com>
> 
> > ---
> >  tools/perf/tests/sample-parsing.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/tools/perf/tests/sample-parsing.c b/tools/perf/tests/sample-parsing.c
> > index f506eabfc269..0dbe3aa99853 100644
> > --- a/tools/perf/tests/sample-parsing.c
> > +++ b/tools/perf/tests/sample-parsing.c
> > @@ -202,7 +202,7 @@ static int do_test(u64 sample_type, u64 sample_regs, u64 read_format)
> >  		.data = {1, -1ULL, 211, 212, 213},
> >  	};
> >  	u64 regs[64];
> > -	const u64 raw_data[] = {0x123456780a0b0c0dULL, 0x1102030405060708ULL};
> > +	const u32 raw_data[] = {0x12345678, 0x0a0b0c0d, 0x11020304, 0x05060708, 0 };
> >  	const u64 data[] = {0x2211443366558877ULL, 0, 0xaabbccddeeff4321ULL};
> >  	const u64 aux_data[] = {0xa55a, 0, 0xeeddee, 0x0282028202820282};
> >  	struct perf_sample sample = {
> > 
> 

-- 

- Arnaldo