4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Thomas Richter tmricht@linux.vnet.ibm.com
[ Upstream commit fca32340a5e8b896f57d41fd94b8b1701df25eb1 ]
Executing command 'perf stat -T -- ls' dumps core on x86 and s390.
Here is the call back chain (done on x86):
# gdb ./perf .... (gdb) r stat -T -- ls ... Program received signal SIGSEGV, Segmentation fault. 0x00007ffff56d1963 in vasprintf () from /lib64/libc.so.6 (gdb) where #0 0x00007ffff56d1963 in vasprintf () from /lib64/libc.so.6 #1 0x00007ffff56ae484 in asprintf () from /lib64/libc.so.6 #2 0x00000000004f1982 in __parse_events_add_pmu (parse_state=0x7fffffffd580, list=0xbfb970, name=0xbf3ef0 "cpu", head_config=0xbfb930, auto_merge_stats=false) at util/parse-events.c:1233 #3 0x00000000004f1c8e in parse_events_add_pmu (parse_state=0x7fffffffd580, list=0xbfb970, name=0xbf3ef0 "cpu", head_config=0xbfb930) at util/parse-events.c:1288 #4 0x0000000000537ce3 in parse_events_parse (_parse_state=0x7fffffffd580, scanner=0xbf4210) at util/parse-events.y:234 #5 0x00000000004f2c7a in parse_events__scanner (str=0x6b66c0 "task-clock,{instructions,cycles,cpu/cycles-t/,cpu/tx-start/}", parse_state=0x7fffffffd580, start_token=258) at util/parse-events.c:1673 #6 0x00000000004f2e23 in parse_events (evlist=0xbe9990, str=0x6b66c0 "task-clock,{instructions,cycles,cpu/cycles-t/,cpu/tx-start/}", err=0x0) at util/parse-events.c:1713 #7 0x000000000044e137 in add_default_attributes () at builtin-stat.c:2281 #8 0x000000000044f7b5 in cmd_stat (argc=1, argv=0x7fffffffe3b0) at builtin-stat.c:2828 #9 0x00000000004c8b0f in run_builtin (p=0xab01a0 <commands+288>, argc=4, argv=0x7fffffffe3b0) at perf.c:297 #10 0x00000000004c8d7c in handle_internal_command (argc=4, argv=0x7fffffffe3b0) at perf.c:349 #11 0x00000000004c8ece in run_argv (argcp=0x7fffffffe20c, argv=0x7fffffffe200) at perf.c:393 #12 0x00000000004c929c in main (argc=4, argv=0x7fffffffe3b0) at perf.c:537 (gdb)
It turns out that a NULL pointer is referenced. Here are the function calls:
... cmd_stat() +---> add_default_attributes() +---> parse_events(evsel_list, transaction_attrs, NULL); 3rd parameter set to NULL
Function parse_events(xx, xx, struct parse_events_error *err) dives into a bison generated scanner and creates parser state information for it first:
struct parse_events_state parse_state = { .list = LIST_HEAD_INIT(parse_state.list), .idx = evlist->nr_entries, .error = err, <--- NULL POINTER !!! .evlist = evlist, };
Now various functions inside the bison scanner are called to end up in __parse_events_add_pmu(struct parse_events_state *parse_state, ..) with first parameter being a pointer to above structure definition.
Now the PMU event name is not found (because being executed in a VM) and this function tries to create an error message with
asprintf(&parse_state->error.str, ....)
which references a NULL pointer and dumps core.
Fix this by providing a pointer to the necessary error information instead of NULL. Technically only the else part is needed to avoid the core dump, just lets be safe...
Signed-off-by: Thomas Richter tmricht@linux.vnet.ibm.com Cc: Heiko Carstens heiko.carstens@de.ibm.com Cc: Hendrik Brueckner brueckner@linux.vnet.ibm.com Cc: Martin Schwidefsky schwidefsky@de.ibm.com Link: http://lkml.kernel.org/r/20180308145735.64717-1-tmricht@linux.vnet.ibm.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 --- tools/perf/builtin-stat.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)
--- a/tools/perf/builtin-stat.c +++ b/tools/perf/builtin-stat.c @@ -2185,11 +2185,16 @@ static int add_default_attributes(void) return 0;
if (transaction_run) { + struct parse_events_error errinfo; + if (pmu_have_event("cpu", "cycles-ct") && pmu_have_event("cpu", "el-start")) - err = parse_events(evsel_list, transaction_attrs, NULL); + err = parse_events(evsel_list, transaction_attrs, + &errinfo); else - err = parse_events(evsel_list, transaction_limited_attrs, NULL); + err = parse_events(evsel_list, + transaction_limited_attrs, + &errinfo); if (err) { fprintf(stderr, "Cannot set up transaction events\n"); return -1;