GHSA-8j5h-5p5c-hg7m

Опубликовано: 21 мая 2024

Источник: github

Github: Не прошло ревью

CVSS3: 5.5

Описание

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:traci...

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!

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.

Ссылки

EPSS

Процентиль: 6%

0.00029

Низкий

5.5 Medium

CVSS3

CVE ID

CVE-2023-52879

Дефекты

CWE-476

Связанные уязвимости

CVE-2023-52879

CVSS3: 5.5

ubuntu

около 1 года назад

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: 1. Change directory to the tracefs directory 2. Create a kprobe event (doesn't matter what one) 3. Open bash file descriptor 5 on the enable file of the kprobe event 4. Delete the kprobe event (removes the files too) 5. 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/0x...