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From: Namhyung Kim <namhyung@kernel.org>
Date: Thu, 25 Jan 2024 15:31:24 -0800
Message-ID: <CAM9d7chePctxu6n5nKkS1w3ju=aTUuzyZfzA1MDBTd+KkzoTEg@mail.gmail.com>
Subject: Re: [PATCH] perf data convert: Output empty string for null pointer
To: Ian Rogers <irogers@google.com>
Cc: kotborealis@awooo.ru, Peter Zijlstra <peterz@infradead.org>, 
	Ingo Molnar <mingo@redhat.com>, Arnaldo Carvalho de Melo <acme@kernel.org>, Mark Rutland <mark.rutland@arm.com>, 
	Alexander Shishkin <alexander.shishkin@linux.intel.com>, Jiri Olsa <jolsa@kernel.org>, 
	Adrian Hunter <adrian.hunter@intel.com>, linux-perf-users@vger.kernel.org, 
	linux-kernel@vger.kernel.org
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Hello,

On Thu, Jan 25, 2024 at 12:59=E2=80=AFPM Ian Rogers <irogers@google.com> wr=
ote:
>
> On Thu, Jan 25, 2024 at 10:44=E2=80=AFAM <kotborealis@awooo.ru> wrote:
> >
> > From: Evgeny Pistun <kotborealis@awooo.ru>
> >
> > Providing ill-formed input to `perf data conver --to-json`
> > causes it to crash with segmentaton fault. There's a bug in
> > `output_json_string` functon: input string is not validated.
> > This could be reproduced by crafting input that does not specify
> > hostname/os-release/etc, which are written to 'headers' section of
> > outputted json.
> >
> > This patch adds a null pointer check. If `output_json_string` is
> > called with a null pointer, it should output empty string (`""`).
> >
> > Signed-off-by: Evgeny Pistun <kotborealis@awooo.ru>
>
> Reviewed-by: Ian Rogers <irogers@google.com>

I think this is related to this one:

  https://lore.kernel.org/linux-perf-users/20240117215101.77713-1-ilkka@os.=
amperecomputing.com/

I'm ok with making it robust, but also afraid it might
end up with a broken JSON if something is missing in
{ key: value } format.  IOW we may need to handle it in
a higher layer.

Thanks,
Namhyung