ghsa-q32w-2qjp-8m8q
Vulnerability from github
Published
2025-10-01 12:30
Modified
2025-10-01 12:30
Details

In the Linux kernel, the following vulnerability has been resolved:

tracing/synthetic: Fix races on freeing last_cmd

Currently, the "last_cmd" variable can be accessed by multiple processes asynchronously when multiple users manipulate synthetic_events node at the same time, it could lead to use-after-free or double-free.

This patch add "lastcmd_mutex" to prevent "last_cmd" from being accessed asynchronously.

================================================================

It's easy to reproduce in the KASAN environment by running the two scripts below in different shells.

script 1: while : do echo -n -e '\x88' > /sys/kernel/tracing/synthetic_events done

script 2: while : do echo -n -e '\xb0' > /sys/kernel/tracing/synthetic_events done

================================================================ double-free scenario:

process A                       process B

------------------- --------------- 1.kstrdup last_cmd 2.free last_cmd 3.free last_cmd(double-free)

================================================================ use-after-free scenario:

process A                       process B

------------------- --------------- 1.kstrdup last_cmd 2.free last_cmd 3.tracing_log_err(use-after-free)

================================================================

Appendix 1. KASAN report double-free:

BUG: KASAN: double-free in kfree+0xdc/0x1d4 Free of addr * by task sh/4879 Call trace: ... kfree+0xdc/0x1d4 create_or_delete_synth_event+0x60/0x1e8 trace_parse_run_command+0x2bc/0x4b8 synth_events_write+0x20/0x30 vfs_write+0x200/0x830 ...

Allocated by task 4879: ... kstrdup+0x5c/0x98 create_or_delete_synth_event+0x6c/0x1e8 trace_parse_run_command+0x2bc/0x4b8 synth_events_write+0x20/0x30 vfs_write+0x200/0x830 ...

Freed by task 5464: ... kfree+0xdc/0x1d4 create_or_delete_synth_event+0x60/0x1e8 trace_parse_run_command+0x2bc/0x4b8 synth_events_write+0x20/0x30 vfs_write+0x200/0x830 ...

================================================================ Appendix 2. KASAN report use-after-free:

BUG: KASAN: use-after-free in strlen+0x5c/0x7c Read of size 1 at addr * by task sh/5483 sh: CPU: 7 PID: 5483 Comm: sh ... __asan_report_load1_noabort+0x34/0x44 strlen+0x5c/0x7c tracing_log_err+0x60/0x444 create_or_delete_synth_event+0xc4/0x204 trace_parse_run_command+0x2bc/0x4b8 synth_events_write+0x20/0x30 vfs_write+0x200/0x830 ...

Allocated by task 5483: ... kstrdup+0x5c/0x98 create_or_delete_synth_event+0x80/0x204 trace_parse_run_command+0x2bc/0x4b8 synth_events_write+0x20/0x30 vfs_write+0x200/0x830 ...

Freed by task 5480: ... kfree+0xdc/0x1d4 create_or_delete_synth_event+0x74/0x204 trace_parse_run_command+0x2bc/0x4b8 synth_events_write+0x20/0x30 vfs_write+0x200/0x830 ...

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{
  "affected": [],
  "aliases": [
    "CVE-2023-53478"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-10-01T12:15:50Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ntracing/synthetic: Fix races on freeing last_cmd\n\nCurrently, the \"last_cmd\" variable can be accessed by multiple processes\nasynchronously when multiple users manipulate synthetic_events node\nat the same time, it could lead to use-after-free or double-free.\n\nThis patch add \"lastcmd_mutex\" to prevent \"last_cmd\" from being accessed\nasynchronously.\n\n================================================================\n\nIt\u0027s easy to reproduce in the KASAN environment by running the two\nscripts below in different shells.\n\nscript 1:\n        while :\n        do\n                echo -n -e \u0027\\x88\u0027 \u003e /sys/kernel/tracing/synthetic_events\n        done\n\nscript 2:\n        while :\n        do\n                echo -n -e \u0027\\xb0\u0027 \u003e /sys/kernel/tracing/synthetic_events\n        done\n\n================================================================\ndouble-free scenario:\n\n    process A                       process B\n-------------------               ---------------\n1.kstrdup last_cmd\n                                  2.free last_cmd\n3.free last_cmd(double-free)\n\n================================================================\nuse-after-free scenario:\n\n    process A                       process B\n-------------------               ---------------\n1.kstrdup last_cmd\n                                  2.free last_cmd\n3.tracing_log_err(use-after-free)\n\n================================================================\n\nAppendix 1. KASAN report double-free:\n\nBUG: KASAN: double-free in kfree+0xdc/0x1d4\nFree of addr ***** by task sh/4879\nCall trace:\n        ...\n        kfree+0xdc/0x1d4\n        create_or_delete_synth_event+0x60/0x1e8\n        trace_parse_run_command+0x2bc/0x4b8\n        synth_events_write+0x20/0x30\n        vfs_write+0x200/0x830\n        ...\n\nAllocated by task 4879:\n        ...\n        kstrdup+0x5c/0x98\n        create_or_delete_synth_event+0x6c/0x1e8\n        trace_parse_run_command+0x2bc/0x4b8\n        synth_events_write+0x20/0x30\n        vfs_write+0x200/0x830\n        ...\n\nFreed by task 5464:\n        ...\n        kfree+0xdc/0x1d4\n        create_or_delete_synth_event+0x60/0x1e8\n        trace_parse_run_command+0x2bc/0x4b8\n        synth_events_write+0x20/0x30\n        vfs_write+0x200/0x830\n        ...\n\n================================================================\nAppendix 2. KASAN report use-after-free:\n\nBUG: KASAN: use-after-free in strlen+0x5c/0x7c\nRead of size 1 at addr ***** by task sh/5483\nsh: CPU: 7 PID: 5483 Comm: sh\n        ...\n        __asan_report_load1_noabort+0x34/0x44\n        strlen+0x5c/0x7c\n        tracing_log_err+0x60/0x444\n        create_or_delete_synth_event+0xc4/0x204\n        trace_parse_run_command+0x2bc/0x4b8\n        synth_events_write+0x20/0x30\n        vfs_write+0x200/0x830\n        ...\n\nAllocated by task 5483:\n        ...\n        kstrdup+0x5c/0x98\n        create_or_delete_synth_event+0x80/0x204\n        trace_parse_run_command+0x2bc/0x4b8\n        synth_events_write+0x20/0x30\n        vfs_write+0x200/0x830\n        ...\n\nFreed by task 5480:\n        ...\n        kfree+0xdc/0x1d4\n        create_or_delete_synth_event+0x74/0x204\n        trace_parse_run_command+0x2bc/0x4b8\n        synth_events_write+0x20/0x30\n        vfs_write+0x200/0x830\n        ...",
  "id": "GHSA-q32w-2qjp-8m8q",
  "modified": "2025-10-01T12:30:30Z",
  "published": "2025-10-01T12:30:30Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-53478"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4ccf11c4e8a8e051499d53a12f502196c97a758e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8826d9e7bd51e7656f78baa4472e8e2f5e7069f0"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9fe183f659a2704255e5d84f6ae308c234a113ec"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}


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