Описание
In the Linux kernel, the following vulnerability has been resolved:
ALSA: seq: oss: Fix UAF at handling events with embedded SysEx data
The OSS sequencer processes the input MIDI bytes into a sequencer
event to be dispatched later (in snd_seq_oss_midi_putc() called from
snd_seq_oss_process_event()). When it's a SysEx data, the event
record contains data.ext.ptr pointer to the original SysEx bytes, and
the referred data is copied into the pool afterwards at dispatching.
The problem is that, if the sequencer port gets closed concurrently
before the dispatch, the OSS sequencer core also releases the
resources (in snd_seq_oss_midi_check_exit_port()), while the pending
event may hold a stale pointer, eventually leading to a UAF at a later
dispatch.
Fortunately, there is already a refcounting mechanism (snd_use_lock_t)
for the OSS MIDI device access, and for addressing the issue above, we
just need to extend the refcount until the event gets dispatched.
This patch extends snd_seq_oss_process_event() to give back the
refcount object, which is in turn released after calling the sequencer
dispatcher with the given event in the caller side.
According to the original report, KASAN report as below:
KASAN slab-use-after-free in snd_seq_event_dup+0x40c/0x470
RIP: 0033:0x7f2cb66a6340
Read of size 6
Call trace:
dump_stack_lvl+0x73/0xb0 (?:?)
print_report+0xd1/0x650 (?:?)
srso_alias_return_thunk+0x5/0xfbef5 (?:?)
__virt_addr_valid+0x1a7/0x340 (?:?)
kasan_complete_mode_report_info+0x64/0x200 (?:?)
kasan_report+0xf7/0x130 (?:?)
snd_seq_event_dup+0x40c/0x470 (?:?)
kasan_check_range+0x10c/0x1c0 (?:?)
__asan_memcpy+0x27/0x70 (?:?)
snd_seq_event_dup+0x9/0x470 (?:?)
snd_seq_client_enqueue_event+0x139/0x240 (?:?)
_raw_spin_unlock_irqrestore+0x4b/0x60 (?:?)
snd_seq_kernel_client_enqueue+0x102/0x120 (?:?)
snd_seq_oss_write+0x416/0x4e0 (?:?)
apparmor_file_permission+0x20/0x30 (?:?)
odev_write+0x3b/0x60 (?:?)
vfs_write+0x1ce/0x850 (?:?)
lock_release+0xc8/0x2a0 (?:?)
__kasan_check_write+0x18/0x20 (?:?)
__mutex_unlock_slowpath+0x129/0x510 (?:?)
ksys_write+0xe1/0x180 (?:?)
mutex_unlock+0x16/0x20 (?:?)
odev_ioctl+0x65/0xc0 (?:?)
__x64_sys_write+0x46/0x60 (?:?)
x64_sys_call+0x7d/0x20d0 (?:?)
do_syscall_64+0xc1/0x360 (arch/x86/entry/syscall_64.c:87)
entry_SYSCALL_64_after_hwframe+0x77/0x7f (?:?)
A flaw was found in the Linux kernel's Advanced Linux Sound Architecture (ALSA) Open Sound System (OSS) sequencer. A local attacker could exploit a Use-After-Free (UAF) vulnerability by concurrently closing a sequencer port while an event containing System Exclusive (SysEx) data is pending dispatch. This could lead to a denial of service or potentially arbitrary code execution.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 10 | kernel | Fix deferred | ||
| Red Hat Enterprise Linux 6 | kernel | Out of support scope | ||
| Red Hat Enterprise Linux 7 | kernel | Fix deferred | ||
| Red Hat Enterprise Linux 7 | kernel-rt | Fix deferred | ||
| Red Hat Enterprise Linux 8 | kernel | Fix deferred | ||
| Red Hat Enterprise Linux 8 | kernel-rt | Fix deferred | ||
| Red Hat Enterprise Linux 9 | kernel | Fix deferred | ||
| Red Hat Enterprise Linux 9 | kernel-rt | Fix deferred |
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Дополнительная информация
Статус:
EPSS
5.5 Medium
CVSS3
Связанные уязвимости
In the Linux kernel, the following vulnerability has been resolved: ALSA: seq: oss: Fix UAF at handling events with embedded SysEx data The OSS sequencer processes the input MIDI bytes into a sequencer event to be dispatched later (in snd_seq_oss_midi_putc() called from snd_seq_oss_process_event()). When it's a SysEx data, the event record contains data.ext.ptr pointer to the original SysEx bytes, and the referred data is copied into the pool afterwards at dispatching. The problem is that, if the sequencer port gets closed concurrently before the dispatch, the OSS sequencer core also releases the resources (in snd_seq_oss_midi_check_exit_port()), while the pending event may hold a stale pointer, eventually leading to a UAF at a later dispatch. Fortunately, there is already a refcounting mechanism (snd_use_lock_t) for the OSS MIDI device access, and for addressing the issue above, we just need to extend the refcount until the event gets dispatched. This patch extends snd_seq_oss_pro...
In the Linux kernel, the following vulnerability has been resolved: ALSA: seq: oss: Fix UAF at handling events with embedded SysEx data The OSS sequencer processes the input MIDI bytes into a sequencer event to be dispatched later (in snd_seq_oss_midi_putc() called from snd_seq_oss_process_event()). When it's a SysEx data, the event record contains data.ext.ptr pointer to the original SysEx bytes, and the referred data is copied into the pool afterwards at dispatching. The problem is that, if the sequencer port gets closed concurrently before the dispatch, the OSS sequencer core also releases the resources (in snd_seq_oss_midi_check_exit_port()), while the pending event may hold a stale pointer, eventually leading to a UAF at a later dispatch. Fortunately, there is already a refcounting mechanism (snd_use_lock_t) for the OSS MIDI device access, and for addressing the issue above, we just need to extend the refcount until the event gets dispatched. This patch extends snd_seq_oss_pr
In the Linux kernel, the following vulnerability has been resolved: A ...
In the Linux kernel, the following vulnerability has been resolved: ALSA: seq: oss: Fix UAF at handling events with embedded SysEx data The OSS sequencer processes the input MIDI bytes into a sequencer event to be dispatched later (in snd_seq_oss_midi_putc() called from snd_seq_oss_process_event()). When it's a SysEx data, the event record contains data.ext.ptr pointer to the original SysEx bytes, and the referred data is copied into the pool afterwards at dispatching. The problem is that, if the sequencer port gets closed concurrently before the dispatch, the OSS sequencer core also releases the resources (in snd_seq_oss_midi_check_exit_port()), while the pending event may hold a stale pointer, eventually leading to a UAF at a later dispatch. Fortunately, there is already a refcounting mechanism (snd_use_lock_t) for the OSS MIDI device access, and for addressing the issue above, we just need to extend the refcount until the event gets dispatched. This patch extends snd_seq_oss...
EPSS
5.5 Medium
CVSS3