阿里云漏洞库

漏洞描述

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

tracing: Restructure trace_clock_global() to never block

It was reported that a fix to the ring buffer recursion detection would

cause a hung machine when performing suspend / resume testing. The

following backtrace was extracted from debugging that case:

Call Trace:

trace_clock_global+0x91/0xa0

__rb_reserve_next+0x237/0x460

ring_buffer_lock_reserve+0x12a/0x3f0

trace_buffer_lock_reserve+0x10/0x50

__trace_graph_return+0x1f/0x80

trace_graph_return+0xb7/0xf0

? trace_clock_global+0x91/0xa0

ftrace_return_to_handler+0x8b/0xf0

? pv_hash+0xa0/0xa0

return_to_handler+0x15/0x30

? ftrace_graph_caller+0xa0/0xa0

? trace_clock_global+0x91/0xa0

? __rb_reserve_next+0x237/0x460

? ring_buffer_lock_reserve+0x12a/0x3f0

? trace_event_buffer_lock_reserve+0x3c/0x120

? trace_event_buffer_reserve+0x6b/0xc0

? trace_event_raw_event_device_pm_callback_start+0x125/0x2d0

? dpm_run_callback+0x3b/0xc0

? pm_ops_is_empty+0x50/0x50

? platform_get_irq_byname_optional+0x90/0x90

? trace_device_pm_callback_start+0x82/0xd0

? dpm_run_callback+0x49/0xc0

With the following RIP:

RIP: 0010:native_queued_spin_lock_slowpath+0x69/0x200

Since the fix to the recursion detection would allow a single recursion to

happen while tracing, this lead to the trace_clock_global() taking a spin

lock and then trying to take it again:

ring_buffer_lock_reserve() {

trace_clock_global() {

arch_spin_lock() {

queued_spin_lock_slowpath() {

/* lock taken */

(something else gets traced by function graph tracer)

ring_buffer_lock_reserve() {

trace_clock_global() {

arch_spin_lock() {

queued_spin_lock_slowpath() {

/* DEAD LOCK! */

Tracing should *never* block, as it can lead to strange lockups like the

above.

Restructure the trace_clock_global() code to instead of simply taking a

lock to update the recorded "prev_time" simply use it, as two events

happening on two different CPUs that calls this at the same time, really

doesn't matter which one goes first. Use a trylock to grab the lock for

updating the prev_time, and if it fails, simply try again the next time.

If it failed to be taken, that means something else is already updating

it.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=212761

解决建议

建议您更新当前系统或软件至最新版，完成漏洞的修复。

参考链接
https://git.kernel.org/stable/c/1fca00920327be96f3318224f502e4d5460f9545
https://git.kernel.org/stable/c/2a1bd74b8186d7938bf004f5603f25b84785f63e
https://git.kernel.org/stable/c/6e2418576228eeb12e7ba82edb8f9500623942ff
https://git.kernel.org/stable/c/859b47a43f5a0e5b9a92b621dc6ceaad39fb5c8b
https://git.kernel.org/stable/c/91ca6f6a91f679c8645d7f3307e03ce86ad518c4
https://git.kernel.org/stable/c/a33614d52e97fc8077eb0b292189ca7d964cc534
https://git.kernel.org/stable/c/aafe104aa9096827a429bc1358f8260ee565b7cc
https://git.kernel.org/stable/c/c64da3294a7d59a4bf6874c664c13be892f15f44
https://git.kernel.org/stable/c/d43d56dbf452ccecc1ec735cd4b6840118005d7c

受影响软件情况

1
#	类型	厂商	产品	版本	影响面
	运行在以下环境
	系统	debian_10	linux	*		Up to (excluding) 4.19.194-1
	运行在以下环境
	系统	debian_11	linux	*		Up to (excluding) 5.10.38-1
	运行在以下环境
	系统	debian_12	linux	*		Up to (excluding) 5.10.38-1
	运行在以下环境
	系统	linux	linux_kernel	*	From (including) 2.6.30	Up to (excluding) 4.4.269
	运行在以下环境
	系统	linux	linux_kernel	*	From (including) 4.10.0	Up to (excluding) 4.14.233
	运行在以下环境
	系统	linux	linux_kernel	*	From (including) 4.15.0	Up to (excluding) 4.19.191
	运行在以下环境
	系统	linux	linux_kernel	*	From (including) 4.20.0	Up to (excluding) 5.4.118
	运行在以下环境
	系统	linux	linux_kernel	*	From (including) 4.5.0	Up to (excluding) 4.9.269
	运行在以下环境
	系统	linux	linux_kernel	*	From (including) 5.11.0	Up to (excluding) 5.11.20
	运行在以下环境
	系统	linux	linux_kernel	*	From (including) 5.12.0	Up to (excluding) 5.12.3
	运行在以下环境
	系统	linux	linux_kernel	*	From (including) 5.5.0	Up to (excluding) 5.10.36

攻击路径

本地
攻击复杂度

困难
权限要求

管控权限
影响范围

有限影响
EXP成熟度

未验证
补丁情况

官方补丁
数据保密性

无影响
数据完整性

无影响
服务器危害

无影响
全网数量

N/A

CWE-ID	漏洞类型
CWE-662	不恰当的同步机制

中危 跟踪：重组trace_clock_global()以永不阻塞(CVE-2021-46939)

漏洞描述

解决建议

参考链接

受影响软件情况

中危跟踪：重组trace_clock_global()以永不阻塞(CVE-2021-46939)