perf: double free in perf test 21 (code-reading.c)

hi,
the alternative setup (when perf_evlist__open fails) calls perf_evlist__delete which releases cpu_maps. And that is not expected byt the test so it segfaults.

Using perf_event_max_sample_rate setup to hit the alternative setup.

thanks,
jirka

[root@krava perf]# echo 1000 > /proc/sys/kernel/perf_event_max_sample_rate
[root@krava perf]# ./perf test 21
21: Test object code reading :Segmentation fault
[root@krava perf]# gdb ./perf
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Reading symbols from /home/jolsa/linux-perf/tools/perf/perf...done.
(gdb) r test 21
Starting program: /home/jolsa/linux-perf/tools/perf/perf test 21
[Thread debugging using libthread_db enabled]
21: Test object code reading :
Program received signal SIGSEGV, Segmentation fault.
0x080907db in __perf_evlist__munmap (idx=14700, evlist=<optimized out>) at util/evlist.c:583
583 evlist->mmap[idx].base = NULL;
Missing separate debuginfos, use: debuginfo-install bzip2-libs-1.0.6-3.fc15.i686 elfutils-libelf-0.152-1.fc15.i686 elfutils-libs-0.152-1.fc15.i686 glibc-2.14.1-6.i686 libgcc-4.6.3-2.fc15.i686 libunwind-0.99-0.16.20090430betagit4b8404d1.fc15.i686 python-libs-2.7.1-7.fc15.i686 slang-2.2.3-2.fc15.i686 xz-libs-5.0.3-1.fc15.i686 zlib-1.2.5-6.fc15.i686 (gdb) bt

#0  0x080907db in __perf_evlist__munmap (idx=14700, evlist=<optimized out>) at util/evlist.c:583
#1  perf_evlist__munmap (evlist=0x82e7c18) at util/evlist.c:595
#2  perf_evlist__delete (evlist=0x82e7c18) at util/evlist.c:110
#3  0x080f3909 in do_test_code_reading (try_kcore=false) at tests/code-reading.c:543
#4  0x080f3d46 in test__code_reading () at tests/code-reading.c:559
#5  0x08087232 in __cmd_test (skiplist=0x0, argv=0xbffff5f8, argc=1) at tests/builtin-test.c:187
#6  cmd_test (argc=1, argv=0xbffff5f8, prefix=0x0) at tests/builtin-test.c:252
#7  0x0805c8de in run_builtin (p=0x821bf10, argc=2, argv=0xbffff5f8) at perf.c:319
#8  0x0805c127 in handle_internal_command (argv=0xbffff5f8, argc=2) at perf.c:376
#9  run_argv (argv=0xbffff498, argcp=0xbffff49c) at perf.c:420

#10 main (argc=2, argv=0xbffff5f8) at perf.c:529
(gdb)

perf_evlist__delete() deletes attached cpu and thread maps but the test is still using them, so remove them from the evlist before deleting it.

---
 tools/perf/tests/code-reading.c | 1 +
 1 file changed, 1 insertion(+)

index 653a8fe..bfb1869 100644
@@ -504,6 +504,7 @@ static int do_test_code_reading(bool try_kcore)
 		if (ret < 0) {
 			if (!excl_kernel) {
 				excl_kernel = true;
+				perf_evlist__set_maps(evlist, NULL, NULL);
 				perf_evlist__delete(evlist);
 				evlist = NULL;
 				continue;

1.8.3.2

thanks,
jirka