From: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
To: Ian Rogers <irogers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
Andi Kleen <ak@linux.intel.com>,
linux-kernel@vger.kernel.org,
Stephane Eranian <eranian@google.com>
Subject: Re: [PATCH 2/2] Avoid raising segv using an obvious null dereference
Date: Thu, 26 Sep 2019 12:24:19 -0300 [thread overview]
Message-ID: <20190926152419.GD10129@kernel.org> (raw)
In-Reply-To: <20190925195924.152834-2-irogers@google.com>
Em Wed, Sep 25, 2019 at 12:59:24PM -0700, Ian Rogers escreveu:
> An optimized build such as:
> make -C tools/perf CLANG=1 CC=clang EXTRA_CFLAGS="-O3
> will turn the dereference operation into a ud2 instruction, raising a SIGILL
> rather than a SIGSEGV. Use raise(..) for correctness and clarity.
>
> Similar issues were addressed in Numfor Mbiziwo-Tiapo's patch:
> https://lkml.org/lkml/2019/7/8/1234
Added:
Cc: Numfor Mbiziwo-Tiapo <nums@google.com>
And:
Cc: Wang Nan <wangnan0@huawei.com>
Fixes: a074865e60ed ("perf tools: Introduce perf hooks")
And:
Committer testing:
Before:
[root@quaco ~]# perf test hooks
55: perf hooks : Ok
[root@quaco ~]# perf test -v hooks
55: perf hooks :
--- start ---
test child forked, pid 17092
SIGSEGV is observed as expected, try to recover.
Fatal error (SEGFAULT) in perf hook 'test'
test child finished with 0
---- end ----
perf hooks: Ok
[root@quaco ~]#
After:
[root@quaco ~]# perf test hooks
55: perf hooks : Ok
[root@quaco ~]# perf test -v hooks
55: perf hooks :
--- start ---
test child forked, pid 17909
SIGSEGV is observed as expected, try to recover.
Fatal error (SEGFAULT) in perf hook 'test'
test child finished with 0
---- end ----
perf hooks: Ok
[root@quaco ~]#
----------------------------------------------------------------------------
Thanks, applied.
- Arnaldo
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
> tools/perf/tests/perf-hooks.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/tools/perf/tests/perf-hooks.c b/tools/perf/tests/perf-hooks.c
> index dbc27199c65e..dd865e0bea12 100644
> --- a/tools/perf/tests/perf-hooks.c
> +++ b/tools/perf/tests/perf-hooks.c
> @@ -19,12 +19,11 @@ static void sigsegv_handler(int sig __maybe_unused)
> static void the_hook(void *_hook_flags)
> {
> int *hook_flags = _hook_flags;
> - int *p = NULL;
>
> *hook_flags = 1234;
>
> /* Generate a segfault, test perf_hooks__recover */
> - *p = 0;
> + raise(SIGSEGV);
> }
>
> int test__perf_hooks(struct test *test __maybe_unused, int subtest __maybe_unused)
> --
> 2.23.0.351.gc4317032e6-goog
--
- Arnaldo
next prev parent reply other threads:[~2019-09-26 15:24 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-25 19:59 [PATCH 1/2] Make _FORTIFY_SOURCE defines dependent on the feature Ian Rogers
2019-09-25 19:59 ` [PATCH 2/2] Avoid raising segv using an obvious null dereference Ian Rogers
2019-09-26 15:24 ` Arnaldo Carvalho de Melo [this message]
2019-10-07 14:49 ` [tip: perf/urgent] perf tests: Avoid raising SEGV using an obvious NULL dereference tip-bot2 for Ian Rogers
2019-09-26 15:18 ` [PATCH 1/2] Make _FORTIFY_SOURCE defines dependent on the feature Arnaldo Carvalho de Melo
2019-10-07 14:49 ` [tip: perf/urgent] libsubcmd: " tip-bot2 for Ian Rogers
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