Commit 9f591fd7 authored Mar 11, 2010 by Arnaldo Carvalho de Melo Committed by Ingo Molnar Mar 11, 2010

perf record: Don't try to find buildids in a zero sized file



Fixing this symptom:

 [acme@mica linux-2.6-tip]$ perf record -a -f
   Fatal: Permission error - are you root?

 Bus error
 [acme@mica linux-2.6-tip]$

I.e. if for some reason no data is collected, in this case a non
root user trying to do systemwide profiling, no data will be
collected, and then we end up trying to mmap a zero sized file
and access the file header, b00m.

Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: <stable@kernel.org>
LKML-Reference: <1268333592-30872-1-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent 639fe4b1

tools/perf/builtin-record.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -395,6 +395,9 @@ static int process_buildids(void)
		{
		u64 size = lseek(output, 0, SEEK_CUR);

		if (size == 0)
		return 0;

		session->fd = output;
		return __perf_session__process_events(session, post_processing_offset,
		size - post_processing_offset,