Re: [PATCH v1 1/4] perf record: Delete session after stopping sideband thread

[Ian Rogers]

On Thu, Feb 29, 2024 at 11:47 PM Ian Rogers <irogers@xxxxxxxxxx> wrote:
>
> The session has a header in it which contains a perf env with
> bpf_progs. The bpf_progs are accessed by the sideband thread and so
> the sideband thread must be stopped before the session is deleted, to
> avoid a use after free.  This error was detected by AddressSanitizer
> in the following:
>
> ```
> ==2054673==ERROR: AddressSanitizer: heap-use-after-free on address 0x61d000161e00 at pc 0x55769289de54 bp 0x7f9df36d4ab0 sp 0x7f9df36d4aa8
> READ of size 8 at 0x61d000161e00 thread T1
>     #0 0x55769289de53 in __perf_env__insert_bpf_prog_info util/env.c:42
>     #1 0x55769289dbb1 in perf_env__insert_bpf_prog_info util/env.c:29
>     #2 0x557692bbae29 in perf_env__add_bpf_info util/bpf-event.c:483
>     #3 0x557692bbb01a in bpf_event__sb_cb util/bpf-event.c:512
>     #4 0x5576928b75f4 in perf_evlist__poll_thread util/sideband_evlist.c:68
>     #5 0x7f9df96a63eb in start_thread nptl/pthread_create.c:444
>     #6 0x7f9df9726a4b in clone3 ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81
>
> 0x61d000161e00 is located 384 bytes inside of 2136-byte region [0x61d000161c80,0x61d0001624d8)
> freed by thread T0 here:
>     #0 0x7f9dfa6d7288 in __interceptor_free libsanitizer/asan/asan_malloc_linux.cpp:52
>     #1 0x557692978d50 in perf_session__delete util/session.c:319
>     #2 0x557692673959 in __cmd_record tools/perf/builtin-record.c:2884
>     #3 0x55769267a9f0 in cmd_record tools/perf/builtin-record.c:4259
>     #4 0x55769286710c in run_builtin tools/perf/perf.c:349
>     #5 0x557692867678 in handle_internal_command tools/perf/perf.c:402
>     #6 0x557692867a40 in run_argv tools/perf/perf.c:446
>     #7 0x557692867fae in main tools/perf/perf.c:562
>     #8 0x7f9df96456c9 in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58
> ```
>
> Fixes: 657ee5531903 ("perf evlist: Introduce side band thread")
> Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>

Note, after this series I'm seeing parallel perf testing being as
reliable as serial but parallel testing is nearly 3 times faster. I
think after these changes land we can make parallel execution the
default.

Thanks,
Ian