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Shuai Xue 3a3dff0a73 perf record: skip synthesize event when open evsel failed 
[ Upstream commit 163e5f2b96 ]

When using perf record with the `--overwrite` option, a segmentation fault
occurs if an event fails to open. For example:

  perf record -e cycles-ct -F 1000 -a --overwrite
  Error:
  cycles-ct:H: PMU Hardware doesn't support sampling/overflow-interrupts. Try 'perf stat'
  perf: Segmentation fault
      #0 0x6466b6 in dump_stack debug.c:366
      #1 0x646729 in sighandler_dump_stack debug.c:378
      #2 0x453fd1 in sigsegv_handler builtin-record.c:722
      #3 0x7f8454e65090 in __restore_rt libc-2.32.so[54090]
      #4 0x6c5671 in __perf_event__synthesize_id_index synthetic-events.c:1862
      #5 0x6c5ac0 in perf_event__synthesize_id_index synthetic-events.c:1943
      #6 0x458090 in record__synthesize builtin-record.c:2075
      #7 0x45a85a in __cmd_record builtin-record.c:2888
      #8 0x45deb6 in cmd_record builtin-record.c:4374
      #9 0x4e5e33 in run_builtin perf.c:349
      #10 0x4e60bf in handle_internal_command perf.c:401
      #11 0x4e6215 in run_argv perf.c:448
      #12 0x4e653a in main perf.c:555
      #13 0x7f8454e4fa72 in __libc_start_main libc-2.32.so[3ea72]
      #14 0x43a3ee in _start ??:0

The --overwrite option implies --tail-synthesize, which collects non-sample
events reflecting the system status when recording finishes. However, when
evsel opening fails (e.g., unsupported event 'cycles-ct'), session->evlist
is not initialized and remains NULL. The code unconditionally calls
record__synthesize() in the error path, which iterates through the NULL
evlist pointer and causes a segfault.

To fix it, move the record__synthesize() call inside the error check block, so
it's only called when there was no error during recording, ensuring that evlist
is properly initialized.

Fixes: 4ea648aec0 ("perf record: Add --tail-synthesize option")
Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2025-12-18 13:54:51 +01:00
arch arm64: dts: qcom: msm8996: add interconnect paths to USB2 controller 2025-12-18 13:54:51 +01:00
block block/mq-deadline: Switch back to a single dispatch list 2025-12-18 13:54:45 +01:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: asymmetric_keys - prevent overflow in asymmetric_key_generate_id 2025-12-18 13:54:47 +01:00
Documentation dt-bindings: clock: qcom,x1e80100-gcc: Add missing USB4 clocks/resets 2025-12-18 13:54:44 +01:00
drivers drm/imagination: Fix reference to devm_platform_get_and_ioremap_resource() 2025-12-18 13:54:51 +01:00
fs ntfs3: Fix uninit buffer allocated by __getname() 2025-12-18 13:54:43 +01:00
include perf: Remove get_perf_callchain() init_nr argument 2025-12-18 13:54:49 +01:00
init init: handle bootloader identifier in kernel parameters 2025-10-19 16:33:50 +02:00
io_uring io_uring/napi: fix io_napi_entry RCU accesses 2025-11-24 10:36:06 +01:00
ipc ipc: fix to protect IPCS lookups using RCU 2025-06-27 11:11:22 +01:00
kernel task_work: Fix NMI race condition 2025-12-18 13:54:50 +01:00
lib maple_tree: fix tracepoint string pointers 2025-12-01 11:43:39 +01:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm mm/huge_memory: fix NULL pointer deference when splitting folio 2025-12-07 06:25:02 +09:00
net sctp: Defer SCTP_DBG_OBJCNT_DEC() to sctp_destroy_sock(). 2025-12-18 13:54:48 +01:00
rust rust: kbuild: workaround rustdoc doctests modifier bug 2025-11-24 10:36:07 +01:00
samples samples: work around glibc redefining some of our defines wrong 2025-12-12 18:37:21 +01:00
scripts kconfig/nconf: Initialize the default locale at startup 2025-12-01 11:43:36 +01:00
security smack: fix bug: setting task label silently ignores input garbage 2025-12-18 13:54:40 +01:00
sound ALSA: usb-audio: Add native DSD quirks for PureAudio DAC series 2025-12-12 18:37:20 +01:00
tools perf record: skip synthesize event when open evsel failed 2025-12-18 13:54:51 +01:00
usr kbuild: uapi: Strip comments before size type check 2025-11-13 15:34:35 -05:00
virt KVM: guest_memfd: Remove bindings on memslot deletion when gmem is dying 2025-11-24 10:36:06 +01:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.clippy.toml rust: give Clippy the minimum supported Rust version 2025-08-01 09:48:44 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore rust: introduce .clippy.toml 2025-03-13 13:01:42 +01:00
.mailmap mailmap: add entry for Thorsten Blum 2024-11-07 14:14:59 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Remove self from DSA entry 2024-11-03 12:52:38 -08:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS staging: rtl8712: Remove driver using deprecated API wext 2025-12-07 06:25:02 +09:00
Makefile Linux 6.12.62 2025-12-12 18:37:22 +01:00
README README: Fix spelling 2024-03-18 03:36:32 -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 reStructuredText 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.