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John Garry fc96ec4d5d perf metricgroup: Fix find_evsel_group() event selector 
The following command segfaults on my x86 broadwell:

  $ ./perf stat  -M frontend_bound,retiring,backend_bound,bad_speculation sleep 1
  WARNING: grouped events cpus do not match, disabling group:
    anon group { raw 0x10e }
    anon group { raw 0x10e }
  perf: util/evsel.c:1596: get_group_fd: Assertion `!(!leader->core.fd)' failed.
  Aborted (core dumped)

The issue shows itself as a use-after-free in evlist__check_cpu_maps(),
whereby the leader of an event selector (evsel) has been deleted (yet we
still attempt to verify for an evsel).

Fundamentally the problem comes from metricgroup__setup_events() ->
find_evsel_group(), and has developed from the previous fix attempt in
commit 9c880c24cb ("perf metricgroup: Fix for metrics containing
duration_time").

The problem now is that the logic in checking if an evsel is in the same
group is subtly broken for the "cycles" event. For the "cycles" event,
the pmu_name is NULL; however the logic in find_evsel_group() may set an
event matched against "cycles" as used, when it should not be.

This leads to a condition where an evsel is set, yet its leader is not.

Fix the check for evsel pmu_name by not matching evsels when either has a
NULL pmu_name.

There is still a pre-existing metric issue whereby the ordering of the
metrics may break the 'stat' function, as discussed at:
https://lore.kernel.org/lkml/49c6fccb-b716-1bf0-18a6-cace1cdb66b9@huawei.com/

Fixes: 9c880c24cb ("perf metricgroup: Fix for metrics containing duration_time")
Signed-off-by: John Garry <john.garry@huawei.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> # On a Thinkpad T450S
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/1623335580-187317-2-git-send-email-john.garry@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2021-06-19 10:06:46 -03:00
arch pci-v5.13-fixes-2 2021-06-18 13:54:11 -07:00
block block-5.13-2021-05-22 2021-05-22 07:40:34 -10:00
certs Kbuild updates for v5.13 (2nd) 2021-05-08 10:00:11 -07:00
crypto async_xor: check src_offs is not NULL before updating it 2021-06-10 19:40:14 -07:00
Documentation mm/slub: clarify verification reporting 2021-06-16 09:24:42 -07:00
drivers Networking fixes for 5.13-rc7, including fixes from wireless, bpf, 2021-06-18 18:55:29 -07:00
fs for-5.13-rc6-tag 2021-06-18 16:39:03 -07:00
include Networking fixes for 5.13-rc7, including fixes from wireless, bpf, 2021-06-18 18:55:29 -07:00
init pid: take a reference when initializing cad_pid 2021-06-05 08:58:11 -07:00
ipc ipc/mqueue, msg, sem: avoid relying on a stack reference past its expiry 2021-05-22 15:09:07 -10:00
kernel Networking fixes for 5.13-rc7, including fixes from wireless, bpf, 2021-06-18 18:55:29 -07:00
lib lib: crc64: fix kernel-doc warning 2021-06-05 08:58:12 -07:00
LICENSES LICENSES: Add the CC-BY-4.0 license 2020-12-08 10:33:27 -07:00
mm mm/sparse: fix check_usemap_section_nr warnings 2021-06-16 09:24:43 -07:00
net Networking fixes for 5.13-rc7, including fixes from wireless, bpf, 2021-06-18 18:55:29 -07:00
samples VFIO fixes for v5.13-rc5 2021-06-03 11:52:24 -07:00
scripts recordmcount: Correct st_shndx handling 2021-06-18 09:09:17 -04:00
security trusted-keys: match tpm_get_ops on all return paths 2021-05-12 22:36:37 +03:00
sound sound fixes for 5.13-rc6 2021-06-11 10:47:10 -07:00
tools perf metricgroup: Fix find_evsel_group() event selector 2021-06-19 10:06:46 -03:00
usr .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
virt KVM: VMX: update vcpu posted-interrupt descriptor when assigning device 2021-05-27 07:58:23 -04:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: use private address for Michel Lespinasse 2021-06-05 08:58:12 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: move Murali Karicheri to credits 2021-04-29 15:47:30 -07:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Networking fixes for 5.13-rc7, including fixes from wireless, bpf, 2021-06-18 18:55:29 -07:00
Makefile Clang feature fix for v5.13-rc7 2021-06-16 08:57:44 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.