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From: Ian Rogers <irogers@google.com>
Date: Thu, 29 Feb 2024 23:50:48 -0800
Message-ID: <CAP-5=fX7JDkyPEXwJGmhYf75EA5KsFQpZ3tC-70hNe8kUnZ=rw@mail.gmail.com>
Subject: Re: [PATCH v1 1/4] perf record: Delete session after stopping
 sideband thread
To: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>, 
	Arnaldo Carvalho de Melo <acme@kernel.org>, Namhyung Kim <namhyung@kernel.org>, 
	Mark Rutland <mark.rutland@arm.com>, 
	Alexander Shishkin <alexander.shishkin@linux.intel.com>, Jiri Olsa <jolsa@kernel.org>, 
	Ian Rogers <irogers@google.com>, Adrian Hunter <adrian.hunter@intel.com>, 
	Christian Brauner <brauner@kernel.org>, James Clark <james.clark@arm.com>, 
	Kan Liang <kan.liang@linux.intel.com>, Tim Chen <tim.c.chen@linux.intel.com>, 
	Athira Rajeev <atrajeev@linux.vnet.ibm.com>, Yicong Yang <yangyicong@hisilicon.com>, 
	Kajol Jain <kjain@linux.ibm.com>, Disha Goel <disgoel@linux.ibm.com>, 
	K Prateek Nayak <kprateek.nayak@amd.com>, Song Liu <songliubraving@fb.com>, 
	linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, 
	bpf@vger.kernel.org
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On Thu, Feb 29, 2024 at 11:47=E2=80=AFPM Ian Rogers <irogers@google.com> wr=
ote:
>
> 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:
>
> ```
> =3D=3D2054673=3D=3DERROR: AddressSanitizer: heap-use-after-free on addres=
s 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 [0x61d0001=
61c80,0x61d0001624d8)
> 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_star=
t_call_main.h:58
> ```
>
> Fixes: 657ee5531903 ("perf evlist: Introduce side band thread")
> Signed-off-by: Ian Rogers <irogers@google.com>

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