From: Adrian Hunter <adrian.hunter@intel.com>
To: Leo Yan <leo.yan@linaro.org>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
Kan Liang <kan.liang@linux.intel.com>,
linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] perf session: Correct buffer copying when peek event
Date: Mon, 7 Jun 2021 08:44:36 +0300 [thread overview]
Message-ID: <587603d3-c707-49d8-08a9-193a22e5e227@intel.com> (raw)
In-Reply-To: <20210605052957.1070720-1-leo.yan@linaro.org>
On 5/06/21 8:29 am, Leo Yan wrote:
> When peek an event, it has a short path and a long path. The short path
> uses the session pointer "one_mmap_addr" to directly fetch event; and
> the long path needs to read out the event header and the followed event
> data from file and fill into the buffer pointer passed through the
> argument "buf".
>
> The issue is in the long path that it copies the event header and event
> data into the same destination address which pointer "buf", this means
> the event header is overwritten. We are just lucky to run into the
> short path in most cases, so we don't hit the issue in the long path.
>
> This patch adds the offset "hdr_sz" to the pointer "buf" when copying
> the event data, so that it can reserve the event header which can be
> used properly by its caller.
>
> Fixes: 5a52f33adf02 ("perf session: Add perf_session__peek_event()")
> Signed-off-by: Leo Yan <leo.yan@linaro.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
> ---
> tools/perf/util/session.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
> index 106b3d60881a..e59242c361ce 100644
> --- a/tools/perf/util/session.c
> +++ b/tools/perf/util/session.c
> @@ -1723,6 +1723,7 @@ int perf_session__peek_event(struct perf_session *session, off_t file_offset,
> if (event->header.size < hdr_sz || event->header.size > buf_sz)
> return -1;
>
> + buf += hdr_sz;
> rest = event->header.size - hdr_sz;
>
> if (readn(fd, buf, rest) != (ssize_t)rest)
>
next prev parent reply other threads:[~2021-06-07 5:44 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-05 5:29 [PATCH] perf session: Correct buffer copying when peek event Leo Yan
2021-06-07 5:44 ` Adrian Hunter [this message]
2021-06-08 11:07 ` Jiri Olsa
2021-06-08 12:47 ` Arnaldo Carvalho de Melo
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