CVE-2023-53478
Estado: ModificadaMedia (4.7)—
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.
================================================================ double-free scenario:
Leer descripción completaMostrar menos
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:
================================================================ Appendix 2. KASAN report use-after-free:
Detalles técnicos trazas, registros y código del informe original
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
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
...
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
...CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
- Puntuación base: 4.7
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.11%
- Percentil entre todas las CVEs puntuadas: 1
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
CWE
- CWE-362
Referencias
JSON original (NVD)
Mostrar
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"value": "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's 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 '\\x88' > /sys/kernel/tracing/synthetic_events\n done\n\nscript 2:\n while :\n do\n echo -n -e '\\xb0' > /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 ..."
}
],
"lastModified": "2026-08-04T10:19:07.963",
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