CVE-2024-42239— Linux kernel 安全漏洞
一分钟漏洞结论
影响对象
Linux Linux
利用判断
尚无明确在野利用证据，仍需结合暴露面评估
建议动作
优先检查厂商安全公告和参考链接中的修复版本；无法立即升级时，限制受影响服务暴露并加强监测。
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel 存在安全漏洞，该漏洞源于 bpf 模块在bpf_timer_cancel调用时，如果回调正在被取消，可能会导致死锁。
影响版本矩阵 8
| 厂商 | 产品 | 版本范围 | 状态 |
|---|---|---|---|
| Linux | Linux | b00628b1c7d595ae5b544e059c27b1f5828314b4< 9369830518688ecd5b08ffc08ab3302ce2b5d0f7 |
affected |
b00628b1c7d595ae5b544e059c27b1f5828314b4< 3e4e8178a8666c56813bd167b848fca0f4c9af0a |
affected | ||
b00628b1c7d595ae5b544e059c27b1f5828314b4< d4523831f07a267a943f0dde844bf8ead7495f13 |
affected | ||
5.15 |
affected | ||
< 5.15 |
unaffected | ||
6.6.41≤ 6.6.* |
unaffected | ||
6.9.10≤ 6.9.* |
unaffected | ||
6.10≤ * |
unaffected |
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一、 漏洞 CVE-2024-42239 基础信息
漏洞信息
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Vulnerability Title
bpf: Fail bpf_timer_cancel when callback is being cancelled
来源: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved:
bpf: Fail bpf_timer_cancel when callback is being cancelled
Given a schedule:
timer1 cb timer2 cb
bpf_timer_cancel(timer2); bpf_timer_cancel(timer1);
Both bpf_timer_cancel calls would wait for the other callback to finish
executing, introducing a lockup.
Add an atomic_t count named 'cancelling' in bpf_hrtimer. This keeps
track of all in-flight cancellation requests for a given BPF timer.
Whenever cancelling a BPF timer, we must check if we have outstanding
cancellation requests, and if so, we must fail the operation with an
error (-EDEADLK) since cancellation is synchronous and waits for the
callback to finish executing. This implies that we can enter a deadlock
situation involving two or more timer callbacks executing in parallel
and attempting to cancel one another.
Note that we avoid incrementing the cancelling counter for the target
timer (the one being cancelled) if bpf_timer_cancel is not invoked from
a callback, to avoid spurious errors. The whole point of detecting
cur->cancelling and returning -EDEADLK is to not enter a busy wait loop
(which may or may not lead to a lockup). This does not apply in case the
caller is in a non-callback context, the other side can continue to
cancel as it sees fit without running into errors.
Background on prior attempts:
Earlier versions of this patch used a bool 'cancelling' bit and used the
following pattern under timer->lock to publish cancellation status.
lock(t->lock);
t->cancelling = true;
mb();
if (cur->cancelling)
return -EDEADLK;
unlock(t->lock);
hrtimer_cancel(t->timer);
t->cancelling = false;
The store outside the critical section could overwrite a parallel
requests t->cancelling assignment to true, to ensure the parallely
executing callback observes its cancellation status.
It would be necessary to clear this cancelling bit once hrtimer_cancel
is done, but lack of serialization introduced races. Another option was
explored where bpf_timer_start would clear the bit when (re)starting the
timer under timer->lock. This would ensure serialized access to the
cancelling bit, but may allow it to be cleared before in-flight
hrtimer_cancel has finished executing, such that lockups can occur
again.
Thus, we choose an atomic counter to keep track of all outstanding
cancellation requests and use it to prevent lockups in case callbacks
attempt to cancel each other while executing in parallel.
来源: CVE Program / CVE List V5
CVSS Information
N/A
来源: CVE Program / CVE List V5
Vulnerability Type
N/A
来源: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
来源: 中国国家信息安全漏洞库 CNNVD
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel 存在安全漏洞，该漏洞源于 bpf 模块在bpf_timer_cancel调用时，如果回调正在被取消，可能会导致死锁。
来源: 中国国家信息安全漏洞库 CNNVD
CVSS Information
N/A
来源: 中国国家信息安全漏洞库 CNNVD
Vulnerability Type
N/A
来源: 中国国家信息安全漏洞库 CNNVD
受影响产品
二、漏洞 CVE-2024-42239 的公开POC
| # | POC 描述 | 源链接 | 神龙链接 |
|---|
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CVE-2024-42239 补丁与修复 (3)
同批安全公告 · Linux · 2024-08-07 · 共 19 条
| CVE-2024-42232 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2024-42249 | 7.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2024-42234 | 7.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2024-42233 | 7.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2024-42235 | 7.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2024-42236 | 7.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2024-42250 | 7.8 HIGH | Linux kernel 安全漏洞 |
| CVE-2024-42247 | 7.5 HIGH | Linux kernel 安全漏洞 |
| CVE-2024-42242 | Linux kernel 安全漏洞 | |
| CVE-2024-42237 | Linux kernel 安全漏洞 | |
| CVE-2024-42238 | Linux kernel 安全漏洞 | |
| CVE-2024-42240 | Linux kernel 安全漏洞 | |
| CVE-2024-42241 | Linux kernel 安全漏洞 | |
| CVE-2024-42244 | Linux kernel 安全漏洞 | |
| CVE-2024-42243 | Linux kernel 安全漏洞 | |
| CVE-2024-42245 | Linux kernel 安全漏洞 | |
| CVE-2024-42246 | Linux kernel 安全漏洞 | |
| CVE-2024-42248 | Linux kernel 安全漏洞 |
IV. Related Vulnerabilities
V. Comments for CVE-2024-42239
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