Goal Reached Thanks to every supporter — we hit 100%!

Goal: 1000 CNY · Raised: 1359 CNY

100%
Buy Us a Coffee

CVE-2024-56770— net/sched: netem: account for backlog updates from child qdisc

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

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netem网络调度器在处理子qdisc时，未能正确更新其qlen值以反映子qdisc的包数量变化，导致在达到配置的sch->limit时错误地停止接受新包，影响网络流量的正常传输。

AI Predicted 5.9 Difficulty: Moderate EPSS 0.27% · P19

Possible ATT&CK Techniques 1 AI

T1498 · Network Denial of Service

Affected Version Matrix 16

VendorProduct Version RangeStatus
Linux Linux 50612537e9ab29693122fab20fc1eed235054ffe< 83c6ab12f08dcc09d4c5ac86fdb89736b28f1d31 affected
50612537e9ab29693122fab20fc1eed235054ffe< 216509dda290f6db92c816dd54b83c1df9da9e76 affected
50612537e9ab29693122fab20fc1eed235054ffe< c2047b0e216c8edce227d7c42f99ac2877dad0e4 affected
50612537e9ab29693122fab20fc1eed235054ffe< 10df49cfca73dfbbdb6c4150d859f7e8926ae427 affected
50612537e9ab29693122fab20fc1eed235054ffe< 3824c5fad18eeb7abe0c4fc966f29959552dca3e affected
50612537e9ab29693122fab20fc1eed235054ffe< 356078a5c55ec8d2061fcc009fb8599f5b0527f9 affected
50612537e9ab29693122fab20fc1eed235054ffe< f8d4bc455047cf3903cd6f85f49978987dbb3027 affected
3.3 affected
… +8 more rows
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2024-56770

Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title
net/sched: netem: account for backlog updates from child qdisc
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: net/sched: netem: account for backlog updates from child qdisc In general, 'qlen' of any classful qdisc should keep track of the number of packets that the qdisc itself and all of its children holds. In case of netem, 'qlen' only accounts for the packets in its internal tfifo. When netem is used with a child qdisc, the child qdisc can use 'qdisc_tree_reduce_backlog' to inform its parent, netem, about created or dropped SKBs. This function updates 'qlen' and the backlog statistics of netem, but netem does not account for changes made by a child qdisc. 'qlen' then indicates the wrong number of packets in the tfifo. If a child qdisc creates new SKBs during enqueue and informs its parent about this, netem's 'qlen' value is increased. When netem dequeues the newly created SKBs from the child, the 'qlen' in netem is not updated. If 'qlen' reaches the configured sch->limit, the enqueue function stops working, even though the tfifo is not full. Reproduce the bug: Ensure that the sender machine has GSO enabled. Configure netem as root qdisc and tbf as its child on the outgoing interface of the machine as follows: $ tc qdisc add dev <oif> root handle 1: netem delay 100ms limit 100 $ tc qdisc add dev <oif> parent 1:0 tbf rate 50Mbit burst 1542 latency 50ms Send bulk TCP traffic out via this interface, e.g., by running an iPerf3 client on the machine. Check the qdisc statistics: $ tc -s qdisc show dev <oif> Statistics after 10s of iPerf3 TCP test before the fix (note that netem's backlog > limit, netem stopped accepting packets): qdisc netem 1: root refcnt 2 limit 1000 delay 100ms Sent 2767766 bytes 1848 pkt (dropped 652, overlimits 0 requeues 0) backlog 4294528236b 1155p requeues 0 qdisc tbf 10: parent 1:1 rate 50Mbit burst 1537b lat 50ms Sent 2767766 bytes 1848 pkt (dropped 327, overlimits 7601 requeues 0) backlog 0b 0p requeues 0 Statistics after the fix: qdisc netem 1: root refcnt 2 limit 1000 delay 100ms Sent 37766372 bytes 24974 pkt (dropped 9, overlimits 0 requeues 0) backlog 0b 0p requeues 0 qdisc tbf 10: parent 1:1 rate 50Mbit burst 1537b lat 50ms Sent 37766372 bytes 24974 pkt (dropped 327, overlimits 96017 requeues 0) backlog 0b 0p requeues 0 tbf segments the GSO SKBs (tbf_segment) and updates the netem's 'qlen'. The interface fully stops transferring packets and "locks". In this case, the child qdisc and tfifo are empty, but 'qlen' indicates the tfifo is at its limit and no more packets are accepted. This patch adds a counter for the entries in the tfifo. Netem's 'qlen' is only decreased when a packet is returned by its dequeue function, and not during enqueuing into the child qdisc. External updates to 'qlen' are thus accounted for and only the behavior of the backlog statistics changes. As in other qdiscs, 'qlen' then keeps track of how many packets are held in netem and all of its children. As before, sch->limit remains as the maximum number of packets in the tfifo. The same applies to netem's backlog statistics.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
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netem网络调度器在处理子qdisc时，未能正确更新其qlen值以反映子qdisc的包数量变化，导致在达到配置的sch->limit时错误地停止接受新包，影响网络流量的正常传输。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 50612537e9ab29693122fab20fc1eed235054ffe ~ 83c6ab12f08dcc09d4c5ac86fdb89736b28f1d31 -
Linux Linux 3.3 -

II. Public POCs for CVE-2024-56770

# POC Description Source Link Shenlong Link
AI-Generated POC Premium

No public POC found.

Login to generate AI POC

III. Intelligence Information for CVE-2024-56770

请登录查看更多情报信息。

Patches & Fixes for CVE-2024-56770 (7)

Same Patch Batch · Linux · 2025-01-08 · 16 CVEs total

CVE-2024-56779 9.8 CRITICAL nfsd: fix nfs4_openowner leak when concurrent nfsd4_open occur
CVE-2024-56775 7.8 HIGH drm/amd/display: Fix handling of plane refcount
CVE-2024-56784 7.8 HIGH drm/amd/display: Adding array index check to prevent memory corruption
CVE-2024-56771 mtd: spinand: winbond: Fix 512GW, 01GW, 01JW and 02JW ECC information
CVE-2024-56773 kunit: Fix potential null dereference in kunit_device_driver_test()
CVE-2024-56772 kunit: string-stream: Fix a UAF bug in kunit_init_suite()
CVE-2024-56774 btrfs: add a sanity check for btrfs root in btrfs_search_slot()
CVE-2024-56776 drm/sti: avoid potential dereference of error pointers
CVE-2024-56777 drm/sti: avoid potential dereference of error pointers in sti_gdp_atomic_check
CVE-2024-56778 drm/sti: avoid potential dereference of error pointers in sti_hqvdp_atomic_check
CVE-2024-56780 quota: flush quota_release_work upon quota writeback
CVE-2024-56782 ACPI: x86: Add adev NULL check to acpi_quirk_skip_serdev_enumeration()
CVE-2024-56783 netfilter: nft_socket: remove WARN_ON_ONCE on maximum cgroup level
CVE-2024-56785 MIPS: Loongson64: DTS: Really fix PCIe port nodes for ls7a
CVE-2024-56787 soc: imx8m: Probe the SoC driver as platform driver

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2024-56770

No comments yet

Leave a comment