CVE-2023-52879

2024-05-2116:15:24

416baaa9-dc9f-4396-8d5f-8c081fb06d67

web.nvd.nist.gov

linux kernel

tracing vulnerability

cve-2023-52879

fix

kernel crash

tracefs

use-after-free

ref counters

6.3 Medium

AI Score

Confidence

Low

0.0004 Low

EPSS

Percentile

10.5%

JSON

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

tracing: Have trace_event_file have ref counters

The following can crash the kernel:

cd /sys/kernel/tracing

echo ‘p:sched schedule’ > kprobe_events

exec 5>>events/kprobes/sched/enable

> kprobe_events

exec 5>&-

The above commands:

Change directory to the tracefs directory
Create a kprobe event (doesn’t matter what one)
Open bash file descriptor 5 on the enable file of the kprobe event
Delete the kprobe event (removes the files too)
Close the bash file descriptor 5

The above causes a crash!

BUG: kernel NULL pointer dereference, address: 0000000000000028
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: 0000 [#1] PREEMPT SMP PTI
CPU: 6 PID: 877 Comm: bash Not tainted 6.5.0-rc4-test-00008-g2c6b6b1029d4-dirty #186
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:tracing_release_file_tr+0xc/0x50

What happens here is that the kprobe event creates a trace_event_file
“file” descriptor that represents the file in tracefs to the event. It
maintains state of the event (is it enabled for the given instance?).
Opening the “enable” file gets a reference to the event “file” descriptor
via the open file descriptor. When the kprobe event is deleted, the file is
also deleted from the tracefs system which also frees the event “file”
descriptor.

But as the tracefs file is still opened by user space, it will not be
totally removed until the final dput() is called on it. But this is not
true with the event “file” descriptor that is already freed. If the user
does a write to or simply closes the file descriptor it will reference the
event “file” descriptor that was just freed, causing a use-after-free bug.

To solve this, add a ref count to the event “file” descriptor as well as a
new flag called “FREED”. The “file” will not be freed until the last
reference is released. But the FREE flag will be set when the event is
removed to prevent any more modifications to that event from happening,
even if there’s still a reference to the event “file” descriptor.

Affected configurations

Vulners

Node

linuxlinux_kernelRange6.6–5.4.262

linuxlinux_kernelRange5.5.0–5.10.202

linuxlinux_kernelRange5.11.0–5.15.140

linuxlinux_kernelRange5.16.0–6.1.64

linuxlinux_kernelRange6.2.0–6.5.13

linuxlinux_kernelRange6.6.0–6.6.1

linuxlinux_kernelRange6.7.0≥

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "include/linux/trace_events.h",
      "kernel/trace/trace.c",
      "kernel/trace/trace.h",
      "kernel/trace/trace_events.c",
      "kernel/trace/trace_events_filter.c"
    ],
    "versions": [
      {
        "version": "e6807c873d87",
        "lessThan": "961c4511c757",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "407bf1c140f0",
        "lessThan": "a98172e36e5f",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "fa6d449e4d02",
        "lessThan": "cbc7c29dff0f",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "a46bf337a20f",
        "lessThan": "2fa74d29fc18",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "9beec0437013",
        "lessThan": "2c9de867ca28",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "f5ca233e2e66",
        "lessThan": "9034c87d61be",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "f5ca233e2e66",
        "lessThan": "bb32500fb9b7",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "include/linux/trace_events.h",
      "kernel/trace/trace.c",
      "kernel/trace/trace.h",
      "kernel/trace/trace_events.c",
      "kernel/trace/trace_events_filter.c"
    ],
    "versions": [
      {
        "version": "6.6",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "6.6",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.4.262",
        "lessThanOrEqual": "5.4.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.10.202",
        "lessThanOrEqual": "5.10.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.15.140",
        "lessThanOrEqual": "5.15.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.1.64",
        "lessThanOrEqual": "6.1.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.5.13",
        "lessThanOrEqual": "6.5.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.6.1",
        "lessThanOrEqual": "6.6.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.7",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]