[PATCH 01/20] perf trace: Check for vfs_getname.pathname length

[Arnaldo Carvalho de Melo]

From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>

It shouldn't be zero, but if the 'perf probe' on getname_flags() (or
elsewhere in the future we need to probe to catch the pathname for
syscalls like 'open' being copied from userspace to the kernel) is
misplaced somehow, then we will end up not allocating space and trying
to copy the "" empty string to ttrace->filename.name, causing a
segfault, fix it.

Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Wang Nan <wangnan0@xxxxxxxxxx>
Link: http://lkml.kernel.org/n/tip-c4f1t6sx1nczuzop19r5si5s@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/builtin-trace.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 912fedc5b42d..33c657c15d5e 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -1656,6 +1656,8 @@ static int trace__vfs_getname(struct trace *trace, struct perf_evsel *evsel,
 		goto out;
 
 	filename_len = strlen(filename);
+	if (filename_len == 0)
+		goto out;
 
 	if (ttrace->filename.namelen < filename_len) {
 		char *f = realloc(ttrace->filename.name, filename_len + 1);
-- 
2.9.3