perf util: Fix bad memory access in trace info.

[ Upstream commit a72f642 ]

In the write to the output_fd in the error condition of
record_saved_cmdline(), we are writing 8 bytes from a memory location on
the stack that contains a primitive that is only 4 bytes in size.
Change the primitive to 8 bytes in size to match the size of the write
in order to avoid reading unknown memory from the stack.

Signed-off-by: Chris Phlipot <cphlipot0@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180829061954.18871-1-cphlipot0@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: cphlipot

tools/perf/util/trace-event-info.c

@@ -379,7 +379,7 @@ static int record_ftrace_printk(void)
 
 static int record_saved_cmdline(void)
 {
-	unsigned int size;
+	unsigned long long size;
 	char *path;
 	struct stat st;
 	int ret, err = 0;