SIGSEGV after tail output for a while

[tangyanhan]

Bug Report

Describe the bug

To Reproduce

• Rubular link if applicable:
• Example log message if applicable:

[2026/01/26 08:31:07] [debug] [input:tail:tail.0] inode=1870784, /var/log/containers/fb-fluent-bit-mcqss_clickhouse_fluent-bit-1172a67e9b7de3df0f67b208980094fa82147be53fd2cb4bcd2dabb97174d246.log, events: IN_MODIFY
[2026/01/26 08:31:07] [debug] [input:tail:tail.0] [static files] processed 0b
[2026/01/26 08:31:07] [debug] [input:tail:tail.0] [static files] processed 0b
[2026/01/26 08:31:07] [debug] [input:tail:tail.0] [static files] processed 0b
[2026/01/26 08:31:07] [debug] [input:tail:tail.0] inode=1870784, /var/log/containers/fb-fluent-bit-mcqss_clickhouse_fluent-bit-1172a67e9b7de3df0f67b208980094fa82147be53fd2cb4bcd2dabb97174d246.log, events: IN_MODIFY
[2026/01/26 08:31:07] [debug] [input:tail:tail.0] [static files] processed 0b
[2026/01/26 08:31:07] [debug] [input:tail:tail.0] inode=1870784, /var/log/containers/fb-fluent-bit-mcqss_clickhouse_fluent-bit-1172a67e9b7de3df0f67b208980094fa82147be53fd2cb4bcd2dabb97174d246.log, events: IN_MODIFY
[2026/01/26 08:31:07] [debug] [input:tail:tail.0] [static files] processed 0b
[2026/01/26 08:31:07] [debug] [input:tail:tail.0] inode=1870784, /var/log/containers/fb-fluent-bit-mcqss_clickhouse_fluent-bit-1172a67e9b7de3df0f67b208980094fa82147be53fd2cb4bcd2dabb97174d246.log, events: IN_MODIFY
[2026/01/26 08:31:07] [engine] caught signal (SIGSEGV)

• Steps to reproduce the problem:

Expected behavior

No SIGSEGV

Screenshots

Your Environment

• Version used: 4.0.5, 4.2.2
• Configuration:

        Rule    $tag ^(atlas_lua)$ atlas false
    [FILTER]
        Name    rewrite_tag
        Match   k8s.*.*.init-preheat
        Rule    $stream ^(.+)$ mizar.preheat false
    [FILTER]
        Name   rewrite_tag
        Match  k8s.mizar-system.mizar-agent*.*
        Rule   $stream  ^(.+)$ mizar.mizar_agent false
        Emitter_Name mizar_agent
    [FILTER]
        Name   rewrite_tag
        Match  k8s.mizar-system.mizar-sylas*.*
        Rule   $stream  ^(.+)$ mizar.mizar_sylas false
        Emitter_Name mizar_sylas
    [FILTER]
        Name    rewrite_tag
        Match   k8s.mizar-system.mizar-aeon*.*
        Rule  $stream ^(.+)$ mizar.mizar_aeon false
    [FILTER]
        Name    rewrite_tag
        Match   k8s.mizar-system.infiniai-controller*.*
        Rule    $stream ^(.+)$ mizar.infiniai_controller false
    [FILTER]
        Name    rewrite_tag
        Match   k8s.clickhouse.adapter*.*
        Rule    $stream ^stderr$ mizar.adapter false
    [FILTER]
        name               log_to_metrics
        match              k8s.clickhouse.fb-fluent-bit*.*
        tag                fail_metric
        metric_mode        counter
        metric_name        ingest_error_count
        regex log level=error.*P=clickhouse
        metric_description This metric counts plugin clickhouse ingest errors

    [OUTPUT]
        Name clickhouse
        ID tenants
        Match k8s.ns-*.*.main
        ConfigFile tenants.toml
    [OUTPUT]
        Name clickhouse
        ID atlas
        Match atlas
        ConfigFile atlas.toml
    [OUTPUT]
        Name clickhouse
        ID mizar_image
        Match k8s.mizar-image.*.main
        ConfigFile mizar-image.toml
    [OUTPUT]
        Name clickhouse
        ID mizar
        Match mizar.*
        ConfigFile mizar.toml
    [OUTPUT]
        Name clickhouse
        ID k8s_events
        Match k8s_events
        ConfigFile k8s_events.toml

• Environment name and version (e.g. Kubernetes? What version?):
  Kubernetes v1.30.14
• Server type and version:
• Operating System and version:
• Filters and plugins:

Additional context

This issue appears after doing an update to fluentbit with tail setting readfromhead to true.