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

From: Vince Weaver <vincent.weaver@maine.edu>
To: linux-kernel@vger.kernel.org
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
	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>
Subject: [patch] perf tool divide by zero error if f_header.attr_size==0
Date: Tue, 23 Jul 2019 11:06:01 -0400 (EDT)	[thread overview]
Message-ID: <alpine.DEB.2.21.1907231100440.14532@macbook-air> (raw)

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.weaver@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);
 
