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fix(driver): use correct syntax for flexible array member#2760

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irozzo-1A merged 1 commit intofalcosecurity:masterfrom
irozzo-1A:fix-flexible-array-synthax
Dec 16, 2025
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fix(driver): use correct syntax for flexible array member#2760
irozzo-1A merged 1 commit intofalcosecurity:masterfrom
irozzo-1A:fix-flexible-array-synthax

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@irozzo-1A irozzo-1A commented Dec 16, 2025 •
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What type of PR is this?

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/kind bug

/kind cleanup

/kind design

/kind documentation

/kind failing-test

/kind test

/kind feature

/kind sync

Any specific area of the project related to this PR?

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/area API-version

/area build

/area CI

/area driver-kmod

/area driver-bpf

/area driver-modern-bpf

/area libscap-engine-bpf

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/area libscap-engine-noop

/area libscap-engine-source-plugin

/area libscap-engine-savefile

/area libscap

/area libpman

/area libsinsp

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Does this PR require a change in the driver versions?

/version driver-API-version-major

/version driver-API-version-minor

/version driver-API-version-patch

/version driver-SCHEMA-version-major

/version driver-SCHEMA-version-minor

/version driver-SCHEMA-version-patch

What this PR does / why we need it:

UBSAN (Undefined Behaviour Sanitizer) performs compile-time and runtime checks based on declared array bounds. Flaxible Array Member used to be declared with the [0] syntax, but should now be expressed with [] syntax to respect C99 standard (§6.7.2.1).

Which issue(s) this PR fixes:

Fixes #2752

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

fix(driver): address UBSAN violation related to Flexible Array Member.

@irozzo-1A
fix(driver): use correct syntax for flexible array member
bbf64c4 
UBSAN (Undefined Behaviour Sanitizer) performs compile-time and runtime
checks based on declared array bounds. Flaxible Array Member used to be
declared with the [0] synthax, but should now be expressed with []
syntax to respect C99 standard (§6.7.2.1).

Signed-off-by: irozzo-1A <iacopo@sysdig.com>
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github-actions bot commented Dec 16, 2025

Please double check driver/API_VERSION file. See versioning.

/hold

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github-actions bot commented Dec 16, 2025

Please double check driver/SCHEMA_VERSION file. See versioning.

/hold

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codecov bot commented Dec 16, 2025 •
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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.57%. Comparing base (d4fb9de) to head (bbf64c4).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files 
@@           Coverage Diff           @@
##           master    #2760   +/-   ##
=======================================
  Coverage   74.57%   74.57%           
=======================================
  Files         292      292           
  Lines       30025    30025           
  Branches     4657     4657           
=======================================
  Hits        22392    22392           
  Misses       7633     7633
Flag Coverage Δ
libsinsp 74.57% <ø> (ø)

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terror96
terror96 reviewed Dec 16, 2025
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driver/ppm_events_public.h
int64_t n_entries;
int64_t max_entries;
struct ppm_proc_info entries[0];
struct ppm_proc_info entries[];
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Good catch, indeed '[]' is the modern, more portable way to define flexible arrays.

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github-actions bot commented Dec 16, 2025

Perf diff from master - unit tests

     4.48%    +13.40%  [.] std::__shared_ptr<sinsp_threadinfo, (__gnu_cxx::_Lock_policy)2>::__shared_ptr(std::__weak_ptr<sinsp_threadinfo, (__gnu_cxx::_Lock_policy)2> const&, std::nothrow_t)
     3.58%    +11.81%  [.] std::__shared_count<(__gnu_cxx::_Lock_policy)2>::_M_get_use_count() const
     4.19%     +9.21%  [.] sinsp_threadinfo::get_main_thread()
     3.35%     +7.98%  [.] sinsp_threadinfo::update_main_fdtable()
     3.51%     +7.52%  [.] std::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_add_ref_lock_nothrow()
     6.01%     +6.32%  [.] std::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_release()
     3.15%     +5.72%  [.] sinsp_threadinfo::get_fd_table()
    11.45%     -5.38%  [.] sinsp::next(sinsp_evt**)
     2.09%     +5.26%  [.] std::__shared_count<(__gnu_cxx::_Lock_policy)2>::__shared_count(std::__weak_count<(__gnu_cxx::_Lock_policy)2> const&, std::nothrow_t)
     1.84%     +3.48%  [.] thread_group_info::get_first_thread() const

Heap diff from master - unit tests

peak heap memory consumption: 27.64K
peak RSS (including heaptrack overhead): 0B
total memory leaked: 0B

Heap diff from master - scap file

peak heap memory consumption: -24B
peak RSS (including heaptrack overhead): 0B
total memory leaked: 0B

Benchmarks diff from master

Comparing gbench_data.json to /root/actions-runner/_work/libs/libs/build/gbench_data.json
Benchmark                                                         Time             CPU      Time Old      Time New       CPU Old       CPU New
----------------------------------------------------------------------------------------------------------------------------------------------
BM_sinsp_split_mean                                            -0.0373         -0.0374           248           238           247           238
BM_sinsp_split_median                                          -0.0373         -0.0374           248           238           247           238
BM_sinsp_split_stddev                                          +0.6871         +0.6381             1             2             1             2
BM_sinsp_split_cv                                              +0.7524         +0.7017             0             0             0             0
BM_sinsp_concatenate_paths_relative_path_mean                  +0.0846         +0.0845            70            76            70            76
BM_sinsp_concatenate_paths_relative_path_median                +0.0935         +0.0934            70            76            69            76
BM_sinsp_concatenate_paths_relative_path_stddev                -0.1572         -0.1576             1             1             1             1
BM_sinsp_concatenate_paths_relative_path_cv                    -0.2229         -0.2232             0             0             0             0
BM_sinsp_concatenate_paths_empty_path_mean                     -0.0691         -0.0692            44            41            44            41
BM_sinsp_concatenate_paths_empty_path_median                   -0.0810         -0.0811            44            40            44            40
BM_sinsp_concatenate_paths_empty_path_stddev                   +0.4902         +0.4915             1             1             1             1
BM_sinsp_concatenate_paths_empty_path_cv                       +0.6008         +0.6023             0             0             0             0
BM_sinsp_concatenate_paths_absolute_path_mean                  +0.0372         +0.0371            71            74            71            74
BM_sinsp_concatenate_paths_absolute_path_median                +0.0357         +0.0356            71            74            71            74
BM_sinsp_concatenate_paths_absolute_path_stddev                +3.8259         +3.9819             0             1             0             1
BM_sinsp_concatenate_paths_absolute_path_cv                    +3.6528         +3.8036             0             0             0             0

@irozzo-1A irozzo-1A marked this pull request as ready for review December 16, 2025 09:52
@poiana poiana requested a review from terror96 December 16, 2025 09:52
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irozzo-1A commented Dec 16, 2025

https://github.com/falcosecurity/libs/actions/runs/20261424717/job/58174173864?pr=2760 is a false positive, this change does not affect the SCHEMA_VERSION

@ekoops ekoops modified the milestones: 0.23.0, next-driver Dec 16, 2025
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/approve

@poiana poiana added the lgtm label Dec 16, 2025
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poiana commented Dec 16, 2025

LGTM label has been added.

DetailsGit tree hash: 6e923e39cd48afe75d362399d2406fd94fa408c9

terror96
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/lgtm

@github-project-automation github-project-automation bot moved this from Todo to In progress in Falco Roadmap Dec 16, 2025
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poiana commented Dec 16, 2025

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ekoops, irozzo-1A, terror96

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@irozzo-1A irozzo-1A merged commit eb2c1a3 into falcosecurity:master Dec 16, 2025
56 of 59 checks passed
@github-project-automation github-project-automation bot moved this from In progress to Done in Falco Roadmap Dec 16, 2025
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Reviewers

@terror96 terror96 terror96 approved these changes

@ekoops ekoops ekoops approved these changes

@hbrueckner hbrueckner Awaiting requested review from hbrueckner

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@terror96 terror96

@ekoops ekoops

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approved area/driver-kmod dco-signoff: yes do-not-merge/hold lgtm release-note size/XS

Projects

Falco Roadmap
Status: Done

Milestone

9.1.0+driver

Development

Successfully merging this pull request may close these issues.

UBSAN: array-index-out-of-bounds in main.c:860:27

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