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    Subject[PATCH 4.9 070/103] perf header: Fix divide by zero error if f_header.attr_size==0
    Date
    [ 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@maine.edu>
    Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
    Cc: Jiri Olsa <jolsa@redhat.com>
    Cc: Namhyung Kim <namhyung@kernel.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Link: http://lkml.kernel.org/r/alpine.DEB.2.21.1907231100440.14532@macbook-air
    Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    tools/perf/util/header.c | 7 +++++++
    1 file changed, 7 insertions(+)

    diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
    index 283148104ffbe..693dcd4ea6a38 100644
    --- a/tools/perf/util/header.c
    +++ b/tools/perf/util/header.c
    @@ -2854,6 +2854,13 @@ 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",
    + 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


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