linux-kernel - Re: [PATCH AUTOSEL 4.4 04/14] perf header: Fix divide by zero error if f_header.attr

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Date:   Mon, 19 Aug 2019 14:07:53 +0200
From:   Jack Wang <jack.wang.usish@...il.com>
To:     Sasha Levin <sashal@...nel.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Vince Weaver <vincent.weaver@...ne.edu>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: Re: [PATCH AUTOSEL 4.4 04/14] perf header: Fix divide by zero error
 if f_header.attr_size==0

Sasha Levin <sashal@...nel.org> 于2019年8月6日周二 下午11:39写道：
>
> From: Vince Weaver <vincent.weaver@...ne.edu>
>
> [ Upstream commit 7622236ceb167aa3857395f9bdaf871442aa467e ]
>
> So I have been having lots of trouble with hand-crafted perf.data files
> causing segfaults and the like, so I have started fuzzing the perf tool.
>
> First issue found:
>
> If f_header.attr_size is 0 in the perf.data file, then perf will crash
> with a divide-by-zero error.
>
> Committer note:
>
> Added a pr_err() to tell the user why the command failed.
>
> Signed-off-by: Vince Weaver <vincent.weaver@...ne.edu>
> Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
> Cc: Jiri Olsa <jolsa@...hat.com>
> Cc: Namhyung Kim <namhyung@...nel.org>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Link: http://lkml.kernel.org/r/alpine.DEB.2.21.1907231100440.14532@macbook-air
> Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
> Signed-off-by: Sasha Levin <sashal@...nel.org>
> ---
>  tools/perf/util/header.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
Hi all,

This on cause build failure when I rebased to 4.14.140-rc1 in stable-rc tree.

    util/header.c: In function 'perf_session__read_header':
    util/header.c:2907:10: error: 'data' undeclared (first use in this
function); did you mean 'dots'?
              data->file.path);
  Should be fixed by:
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -2904,7 +2904,7 @@ int perf_session__read_header(struct
perf_session *session)
        if (f_header.attr_size == 0) {
                pr_err("ERROR: The %s file's attr size field is 0
which is unexpected.\n"
                       "Was the 'perf record' command properly terminated?\n",
-                      data->file.path);
+                      file->path);
                return -EINVAL;

Regards,
Jack Wang

> diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
> index 304f5d7101436..0102dd46fb6da 100644
> --- a/tools/perf/util/header.c
> +++ b/tools/perf/util/header.c
> @@ -2591,6 +2591,13 @@ int perf_session__read_header(struct perf_session *session)
>                            file->path);
>         }
>
> +       if (f_header.attr_size == 0) {
> +               pr_err("ERROR: The %s file's attr size field is 0 which is unexpected.\n"
> +                      "Was the 'perf record' command properly terminated?\n",
> +                      data->file.path);
> +               return -EINVAL;
> +       }
> +
>         nr_attrs = f_header.attrs.size / f_header.attr_size;
>         lseek(fd, f_header.attrs.offset, SEEK_SET);
>
> --
> 2.20.1
>