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From:   "Lubashev, Igor" <ilubashe@akamai.com>
To:     Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>,
        Mathieu Poirier <mathieu.poirier@linaro.org>
CC:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Jiri Olsa <jolsa@redhat.com>,
        Alexey Budankov <alexey.budankov@linux.intel.com>,
        "Peter Zijlstra" <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        "Alexander Shishkin" <alexander.shishkin@linux.intel.com>,
        Namhyung Kim <namhyung@kernel.org>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        Leo Yan <leo.yan@linaro.org>
Subject: RE: [PATCH v3 3/4] perf: Use CAP_SYSLOG with kptr_restrict checks
Thread-Topic: [PATCH v3 3/4] perf: Use CAP_SYSLOG with kptr_restrict checks
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Date:   Tue, 27 Aug 2019 01:58:35 +0000
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On Tue, August 20, 2019 at 1:14 PM Arnaldo Carvalho de Melo <arnaldo.melo@g=
mail.com> wrote:
> > Arnaldo, once we decide what the right fix is, I am happy to post the
> update (options 1, 1+2) as a patch series.
>=20
> I think you should get the checks for ref_reloc_sym in place so as to mak=
e the
> code overall more robust, and also go on continuing to make the checks in
> tools/perf/ to match what is checked on the other side of the mirror, i.e=
. by
> the kernel, so from a quick read, please put first the robustness patches
> (check ref_reloc_sym) do your other suggestions and update the warnings,
> then refresh the two patches that still are not in my perf/core branch:
>=20
> [acme@quaco perf]$ git rebase perf/core
> First, rewinding head to replay your work on top of it...
> Applying: perf tools: Use CAP_SYS_ADMIN with perf_event_paranoid checks
> Applying: perf symbols: Use CAP_SYSLOG with kptr_restrict checks
> [acme@quaco perf]$
>=20
> I've pushed out perf/cap, so you can go from there as it is rebased on my
> current perf/core.
>=20
> Then test all these cases: with/without libcap, with euid=3D=3D0 and diff=
erent
> than zero, with capabilities, etc, patch by patch so that we don't break
> bisection nor regress,

All done.  I've posted the update as a new follow-up series: https://lkml.k=
ernel.org/lkml/1566869956-7154-1-git-send-email-ilubashe@akamai.com/ rebase=
d on your perf/core.

I've tested 336 permutations (see the new cover).  In particular, I was abl=
e to reproduce the crash on perf/cap and confirm that no permutation can ca=
use such crashes for any of the patches in the series.

> Thanks and keep up the good work!
>=20
> - Arnaldo

- Igor