From: Yang Jihong yangjihong1@huawei.com
[ Upstream commit 91621be65d6812cd74b2ea09573ff9ee0cbf5666 ]
When --overwrite and --max-size options of perf record are used together, a segmentation fault occurs. The following is an example:
# perf record -e sched:sched* --overwrite --max-size 1K -a -- sleep 1 [ perf record: Woken up 1 times to write data ] perf: Segmentation fault Obtained 12 stack frames. ./perf/perf(+0x197673) [0x55f99710b673] /lib/x86_64-linux-gnu/libc.so.6(+0x3ef0f) [0x7fa45f3cff0f] ./perf/perf(+0x8eb40) [0x55f997002b40] ./perf/perf(+0x1f6882) [0x55f99716a882] ./perf/perf(+0x794c2) [0x55f996fed4c2] ./perf/perf(+0x7b7c7) [0x55f996fef7c7] ./perf/perf(+0x9074b) [0x55f99700474b] ./perf/perf(+0x12e23c) [0x55f9970a223c] ./perf/perf(+0x12e54a) [0x55f9970a254a] ./perf/perf(+0x7db60) [0x55f996ff1b60] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xe6) [0x7fa45f3b2c86] ./perf/perf(+0x7dfe9) [0x55f996ff1fe9] Segmentation fault (core dumped)
backtrace of the core file is as follows:
(gdb) bt #0 record__bytes_written (rec=0x55f99755a200 <record>) at builtin-record.c:234 #1 record__output_max_size_exceeded (rec=0x55f99755a200 <record>) at builtin-record.c:242 #2 record__write (map=0x0, size=12816, bf=0x55f9978da2e0, rec=0x55f99755a200 <record>) at builtin-record.c:263 #3 process_synthesized_event (tool=tool@entry=0x55f99755a200 <record>, event=event@entry=0x55f9978da2e0, sample=sample@entry=0x0, machine=machine@entry=0x55f997893658) at builtin-record.c:618 #4 0x000055f99716a883 in __perf_event__synthesize_id_index (tool=tool@entry=0x55f99755a200 <record>, process=process@entry=0x55f997002aa0 <process_synthesized_event>, evlist=0x55f9978928b0, machine=machine@entry=0x55f997893658, from=from@entry=0) at util/synthetic-events.c:1895 #5 0x000055f99716a91f in perf_event__synthesize_id_index (tool=tool@entry=0x55f99755a200 <record>, process=process@entry=0x55f997002aa0 <process_synthesized_event>, evlist=<optimized out>, machine=machine@entry=0x55f997893658) at util/synthetic-events.c:1905 #6 0x000055f996fed4c3 in record__synthesize (tail=tail@entry=true, rec=0x55f99755a200 <record>) at builtin-record.c:1997 #7 0x000055f996fef7c8 in __cmd_record (argc=argc@entry=2, argv=argv@entry=0x7ffc67551260, rec=0x55f99755a200 <record>) at builtin-record.c:2802 #8 0x000055f99700474c in cmd_record (argc=<optimized out>, argv=0x7ffc67551260) at builtin-record.c:4258 #9 0x000055f9970a223d in run_builtin (p=0x55f997564d88 <commands+264>, argc=10, argv=0x7ffc67551260) at perf.c:330 #10 0x000055f9970a254b in handle_internal_command (argc=10, argv=0x7ffc67551260) at perf.c:384 #11 0x000055f996ff1b61 in run_argv (argcp=<synthetic pointer>, argv=<synthetic pointer>) at perf.c:428 #12 main (argc=<optimized out>, argv=0x7ffc67551260) at perf.c:562
The reason is that record__bytes_written accesses the freed memory rec->thread_data, The process is as follows: __cmd_record -> record__free_thread_data -> zfree(&rec->thread_data) // free rec->thread_data -> record__synthesize -> perf_event__synthesize_id_index -> process_synthesized_event -> record__write -> record__bytes_written // access rec->thread_data
We add a member variable "thread_bytes_written" in the struct "record" to save the data size written by the threads.
Fixes: 6d57581659f72299 ("perf record: Add support for limit perf output file size") Signed-off-by: Yang Jihong yangjihong1@huawei.com Acked-by: Namhyung Kim namhyung@kernel.org Cc: Alexander Shishkin alexander.shishkin@linux.intel.com Cc: Ingo Molnar mingo@redhat.com Cc: Jiri Olsa jolsa@kernel.org Cc: Jiwei Sun jiwei.sun@windriver.com Cc: Mark Rutland mark.rutland@arm.com Cc: Peter Zijlstra peterz@infradead.org Link: https://lore.kernel.org/r/CAM9d7ci_TRrqBQVQNW8=GwakUr7SsZpYxaaty-S4bxF8zJWyq... Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- tools/perf/builtin-record.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-)
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c index 59f3d98a0196d..48c3461b496c4 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -154,6 +154,7 @@ struct record { struct perf_tool tool; struct record_opts opts; u64 bytes_written; + u64 thread_bytes_written; struct perf_data data; struct auxtrace_record *itr; struct evlist *evlist; @@ -226,14 +227,7 @@ static bool switch_output_time(struct record *rec)
static u64 record__bytes_written(struct record *rec) { - int t; - u64 bytes_written = rec->bytes_written; - struct record_thread *thread_data = rec->thread_data; - - for (t = 0; t < rec->nr_threads; t++) - bytes_written += thread_data[t].bytes_written; - - return bytes_written; + return rec->bytes_written + rec->thread_bytes_written; }
static bool record__output_max_size_exceeded(struct record *rec) @@ -255,10 +249,12 @@ static int record__write(struct record *rec, struct mmap *map __maybe_unused, return -1; }
- if (map && map->file) + if (map && map->file) { thread->bytes_written += size; - else + rec->thread_bytes_written += size; + } else { rec->bytes_written += size; + }
if (record__output_max_size_exceeded(rec) && !done) { fprintf(stderr, "[ perf record: perf size limit reached (%" PRIu64 " KB),"