[PATCH 4.19 32/85] perf header: Fix divide by zero error if f_header.attr_size==0

Greg Kroah-Hartman
2019-08-22T17:32:35Z

[ 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 a94bd6850a0b2..4a5e1907a7ab3 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -3285,6 +3285,13 @@ int perf_session__read_header(struct perf_session *session)
data->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