Re: [PATCH] perf buildid-list: Initialize zstd_data

[Milian Wolff <milian.wolff@kdab.com>]

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On Donnerstag, 29. April 2021 20:57:59 CEST Milian Wolff wrote:
> Fixes segmentation fault when trying to obtain buildid list (e.g. via
> perf-archive) from a zstd-compressed `perf.data` file:

Ping, can someone please review and push this upstream? It's such a trivial 
fix, I would like to see it fixed upstream.

Thanks

> ```
>     $ perf record -z ls
>     ...
>     [ perf record: Captured and wrote 0,010 MB perf.data, compressed
> (original 0,001 MB, ratio is 2,190) ] $ memcheck perf buildid-list
>     ...
>     ==57268== Invalid read of size 4
>     ==57268==    at 0x5260D88: ZSTD_decompressStream (in
> /usr/lib/libzstd.so.1.4.9) ==57268==    by 0x4BB51B: zstd_decompress_stream
> (zstd.c:100)
>     ==57268==    by 0x425C6C: perf_session__process_compressed_event
> (session.c:73) ==57268==    by 0x427450: perf_session__process_user_event
> (session.c:1631) ==57268==    by 0x42A609: reader__process_events
> (session.c:2207) ==57268==    by 0x42A609: __perf_session__process_events
> (session.c:2264) ==57268==    by 0x42A609: perf_session__process_events
> (session.c:2297) ==57268==    by 0x343A62: perf_session__list_build_ids
> (builtin-buildid-list.c:88) ==57268==    by 0x343A62: cmd_buildid_list
> (builtin-buildid-list.c:120) ==57268==    by 0x3C7732: run_builtin
> (perf.c:313)
>     ==57268==    by 0x331157: handle_internal_command (perf.c:365)
>     ==57268==    by 0x331157: run_argv (perf.c:409)
>     ==57268==    by 0x331157: main (perf.c:539)
>     ==57268==  Address 0x7470 is not stack'd, malloc'd or (recently) free'd
> ```
> 
> Signed-off-by: Milian Wolff <milian.wolff@kdab.com>
> ---
>  tools/perf/builtin-buildid-list.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/tools/perf/builtin-buildid-list.c
> b/tools/perf/builtin-buildid-list.c index 87f5b1a4a7fa..833405c27dae 100644
> --- a/tools/perf/builtin-buildid-list.c
> +++ b/tools/perf/builtin-buildid-list.c
> @@ -80,6 +80,9 @@ static int perf_session__list_build_ids(bool force, bool
> with_hits) if (!perf_header__has_feat(&session->header, HEADER_BUILD_ID))
>  		with_hits = true;
> 
> +	if (zstd_init(&(session->zstd_data), 0) < 0)
> +		pr_warning("Decompression initialization failed. Reported data 
may be
> incomplete.\n"); +
>  	/*
>  	 * in pipe-mode, the only way to get the buildids is to parse
>  	 * the record stream. Buildids are stored as RECORD_HEADER_BUILD_ID


-- 
Milian Wolff | milian.wolff@kdab.com | Senior Software Engineer
KDAB (Deutschland) GmbH, a KDAB Group company
Tel: +49-30-521325470
KDAB - The Qt, C++ and OpenGL Experts

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