tools/perf/builtin-record.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-)
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: 6d57581659f7 ("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>
---
Changes since v3:
- Add Namhyung Kim Acked-by
(I don't know whether the problem is caused by my email address, Send again)
Changes since v2:
- Save data size written by threads to calculate the correct total data size.
- Update commit message.
Changes since v1:
- Add variable check in record__bytes_written for code hardening.
- Save bytes_written separately to reduce one calculation.
- Remove rec->opts.tail_synthesize check.
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 29dcd454b8e2..8374117e66f6 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),"
--
2.30.GITEm Wed, Feb 15, 2023 at 12:23:24PM +0000, Yang Jihong escreveu:
> When --overwrite and --max-size options of perf record are used together,
> a segmentation fault occurs. The following is an example:
<SNIP>
> We add a member variable "thread_bytes_written" in the struct "record"
> to save the data size written by the threads.
>
> Fixes: 6d57581659f7 ("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>
> ---
>
> Changes since v3:
> - Add Namhyung Kim Acked-by
> (I don't know whether the problem is caused by my email address, Send again)
Thanks, applied.
- Arnaldo
> Changes since v2:
> - Save data size written by threads to calculate the correct total data size.
> - Update commit message.
>
> Changes since v1:
> - Add variable check in record__bytes_written for code hardening.
> - Save bytes_written separately to reduce one calculation.
> - Remove rec->opts.tail_synthesize check.
>
> 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 29dcd454b8e2..8374117e66f6 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),"
> --
> 2.30.GIT
>
--
- Arnaldo
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