[patch] perf tool divide by zero error if f_header.attr_size==0

[Vince Weaver]

Hello

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.

Signed-off-by: Vince Weaver <vincent.wea...@maine.edu>

diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index c24db7f4909c..26df60ee9460 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -3559,6 +3559,10 @@ int perf_session__read_header(struct perf_session 
*session)
                           data->file.path);
        }
 
+       if (f_header.attr_size == 0) {
+               return -EINVAL;
+       }
+
        nr_attrs = f_header.attrs.size / f_header.attr_size;
        lseek(fd, f_header.attrs.offset, SEEK_SET);