linux-kernel - Re: perf --help triggers an assertion

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Message-ID: <aMMq7I5TBoL7SX6z@x1>
Date: Thu, 11 Sep 2025 17:02:52 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Guilherme Amadio <amadio@...too.org>
Cc: Ian Rogers <irogers@...gle.com>, namhyung@...nel.org,
	adrian.hunter@...el.com, jolsa@...nel.org,
	kan.liang@...ux.intel.com, linux-kernel@...r.kernel.org,
	linux-perf-users@...r.kernel.org, mingo@...nel.org,
	peterz@...radead.org
Subject: Re: perf --help triggers an assertion

On Wed, Sep 10, 2025 at 02:52:25PM +0200, Guilherme Amadio wrote:
> On Tue, Sep 09, 2025 at 11:31:51AM -0700, Ian Rogers wrote:
> > On Tue, Sep 9, 2025 at 2:49 AM Guilherme Amadio <amadio@...too.org> wrote:
> > > I was updating perf's package in Gentoo Linux and noticed some problems
> > > which were not there before. I tested with the version below and the problem
> > > still seems to be there. perf --help triggers an assertion (see below).
> > > Looking in the list, it seems related to the patch below:

> > > https://lore.kernel.org/linux-perf-users/20250701201027.1171561-3-namhyung@kernel.org/

<SNIP>

> > I tried to reproduce the same version with various options: DEBUG=1
> > -UNDEBUG in EXTRA_CFLAGS, -fsanitize=address. Being in various
> > directories with "perf-" prefixed files. I'm afraid I wasn't able to
> > reproduce. The assert is trying to avoid a memory leak, so
> > non-critical, and I couldn't in a quick inspection eye-ball an issue.
> > Without getting a reproduction I don't think I can make progress with
> > the issue.
 
> I do not have any special setup on my machine (if you consider Gentoo
> not special, of course). I just did a git bisect and arrived at commit
> 9401d1771dad99bfc795dd2ae0c292343fd1f78d, which is the commit I linked
> above. I used>

⬢ [acme@...lbx perf-tools-next]$ git show 9401d1771dad99bfc795dd2ae0c292343fd1f78d
fatal: bad object 9401d1771dad99bfc795dd2ae0c292343fd1f78d
⬢ [acme@...lbx perf-tools-next]$ 

Looking for the patch title I got to this one:

commit 1fdf938168c4d26fa279d4f204768690d1f9c4ae
Author: Namhyung Kim <namhyung@...nel.org>
Date:   Tue Jul 1 13:10:27 2025 -0700

    perf tools: Fix use-after-free in help_unknown_cmd()

?

- Arnaldo
 
> $ make -C tools/perf clean && make -B -j16 -C tools/perf DEBUG=1 WERROR=0 NO_SHELLCHECK=1
> 
> then called perf --help each time (but perf help record or equivalent
> also triggers the assertion). I'm using GCC 14 on a 3950X. The features
> I have enabled and installed dependencies are below. This patch has been
> backported to at least 6.12 stable, and I can reproduce this with
> v6.12.45.
> 
> gentoo linux $ tools/perf/perf version --build-options
> perf version 6.16.g45effee4b85a
>                    aio: [ on  ]  # HAVE_AIO_SUPPORT
>                    bpf: [ on  ]  # HAVE_LIBBPF_SUPPORT
>          bpf_skeletons: [ on  ]  # HAVE_BPF_SKEL
>             debuginfod: [ on  ]  # HAVE_DEBUGINFOD_SUPPORT
>                  dwarf: [ on  ]  # HAVE_LIBDW_SUPPORT
>     dwarf_getlocations: [ on  ]  # HAVE_LIBDW_SUPPORT
>           dwarf-unwind: [ on  ]  # HAVE_DWARF_UNWIND_SUPPORT
>               auxtrace: [ on  ]  # HAVE_AUXTRACE_SUPPORT
>                 libbfd: [ OFF ]  # HAVE_LIBBFD_SUPPORT ( tip: Deprecated, license incompatibility, use BUILD_NONDISTRO=1 and install binutils-dev[el] )
>            libcapstone: [ on  ]  # HAVE_LIBCAPSTONE_SUPPORT
>              libcrypto: [ on  ]  # HAVE_LIBCRYPTO_SUPPORT
>     libdw-dwarf-unwind: [ on  ]  # HAVE_LIBDW_SUPPORT
>                 libelf: [ on  ]  # HAVE_LIBELF_SUPPORT
>                libnuma: [ on  ]  # HAVE_LIBNUMA_SUPPORT
>             libopencsd: [ OFF ]  # HAVE_CSTRACE_SUPPORT
>                libperl: [ on  ]  # HAVE_LIBPERL_SUPPORT
>                libpfm4: [ on  ]  # HAVE_LIBPFM
>              libpython: [ on  ]  # HAVE_LIBPYTHON_SUPPORT
>               libslang: [ on  ]  # HAVE_SLANG_SUPPORT
>          libtraceevent: [ on  ]  # HAVE_LIBTRACEEVENT
>              libunwind: [ OFF ]  # HAVE_LIBUNWIND_SUPPORT ( tip: Deprecated, use LIBUNWIND=1 and install libunwind-dev[el] to build with it )
>                   lzma: [ on  ]  # HAVE_LZMA_SUPPORT
> numa_num_possible_cpus: [ on  ]  # HAVE_LIBNUMA_SUPPORT
>                   zlib: [ on  ]  # HAVE_ZLIB_SUPPORT
>                   zstd: [ on  ]  # HAVE_ZSTD_SUPPORT
> 
> And here are the version of all dependencies I have installed:
> 
>  * dependency graph for dev-util/perf-6.16-r1
>  `--  dev-util/perf-6.16-r1
>    `--  dev-util/babeltrace-1.5.11
>    `--  dev-libs/libbpf-1.6.2
>    `--  dev-util/bpftool-7.6.0
>    `--  dev-util/pahole-1.30
>    `--  llvm-core/clang-18.1.8-r6
>    `--  llvm-core/llvm-18.1.8-r6
>    `--  llvm-core/clang-19.1.7
>    `--  llvm-core/llvm-19.1.7
>    `--  llvm-core/clang-20.1.8
>    `--  llvm-core/llvm-20.1.8
>    `--  llvm-core/clang-21.1.0
>    `--  llvm-core/llvm-21.1.0
>    `--  sys-libs/libcap-2.76
>    `--  dev-libs/capstone-5.0.6
>    `--  dev-libs/openssl-3.5.2
>    `--  x11-libs/gtk+-2.24.33-r3
>    `--  virtual/jre-21
>    `--  dev-libs/libpfm-4.13.0
>    `--  dev-libs/libtraceevent-1.8.4
>    `--  dev-libs/libtracefs-1.8.2
>    `--  app-arch/xz-utils-5.8.1-r1
>    `--  sys-process/numactl-2.0.19
>    `--  dev-lang/perl-5.42.0
>    `--  dev-lang/python-0.3.13.7
>    `--  dev-lang/python-0.3.14.0_rc2
>    `--  dev-lang/python-3.11.13_p1
>    `--  dev-lang/python-3.12.11_p1
>    `--  dev-lang/python-3.13.9999
>    `--  dev-lang/python-3.14.0_rc2
>    `--  sys-libs/slang-2.3.3-r1
>    `--  dev-debug/systemtap-5.3
>    `--  dev-util/google-perftools-2.17.2
>    `--  sys-libs/libunwind-1.8.2-r1
>    `--  app-arch/zstd-1.5.7-r1
>    `--  dev-libs/elfutils-0.193
>    `--  sys-libs/binutils-libs-2.45-r1
>    `--  sys-libs/zlib-1.3.1-r1
>    `--  virtual/libcrypt-2-r1
>    `--  sys-kernel/linux-headers-6.16
>    `--  virtual/jdk-21
>    `--  app-arch/tar-1.35
>    `--  dev-python/setuptools-80.9.0-r1
>    `--  app-alternatives/yacc-1-r2
>    `--  app-alternatives/lex-0-r1
>    `--  sys-apps/which-2.23
>    `--  virtual/pkgconfig-3
>    `--  app-text/asciidoc-10.2.1
>    `--  app-text/sgml-common-0.6.3-r7
>    `--  app-text/xmlto-0.0.28-r11
>    `--  sys-process/time-1.9-r1
> 
> I hope that this helps with reproducing the problem, but if not, let me
> know which additional information you'd like to have and I will send it.
> My running kernel is 6.16.4, and glibc is version 2.42.
> 
> Best regards,
> -Guilherme