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CVE-2021-47125— sch_htb: fix refcount leak in htb_parent_to_leaf_offload

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 sch_htb 模块的 htb_parent_to_leaf_offload 方法中存在引用计数泄漏。

AI Predicted 5.5 Difficulty: Moderate EPSS 0.19% · P8

Possible ATT&CK Techniques 1 AI

T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 6

VendorProduct Version RangeStatus
Linux Linux ae81feb7338c89cee4e6aa0424bdab2ce2b52da2< 2411c02d03892a5057499f8102d0cc1e0f852416 affected
ae81feb7338c89cee4e6aa0424bdab2ce2b52da2< 944d671d5faa0d78980a3da5c0f04960ef1ad893 affected
5.12 affected
< 5.12 unaffected
5.12.10≤ 5.12.* unaffected
5.13≤ * unaffected
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I. Basic Information for CVE-2021-47125

Vulnerability Information
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Vulnerability Title
sch_htb: fix refcount leak in htb_parent_to_leaf_offload
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: sch_htb: fix refcount leak in htb_parent_to_leaf_offload The commit ae81feb7338c ("sch_htb: fix null pointer dereference on a null new_q") fixes a NULL pointer dereference bug, but it is not correct. Because htb_graft_helper properly handles the case when new_q is NULL, and after the previous patch by skipping this call which creates an inconsistency : dev_queue->qdisc will still point to the old qdisc, but cl->parent->leaf.q will point to the new one (which will be noop_qdisc, because new_q was NULL). The code is based on an assumption that these two pointers are the same, so it can lead to refcount leaks. The correct fix is to add a NULL pointer check to protect qdisc_refcount_inc inside htb_parent_to_leaf_offload.
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 sch_htb 模块的 htb_parent_to_leaf_offload 方法中存在引用计数泄漏。
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 ae81feb7338c89cee4e6aa0424bdab2ce2b52da2 ~ 2411c02d03892a5057499f8102d0cc1e0f852416 -
Linux Linux 5.12 -

II. Public POCs for CVE-2021-47125

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III. Intelligence Information for CVE-2021-47125

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Other References for CVE-2021-47125 (2)

Same Patch Batch · Linux · 2024-03-15 · 26 CVEs total

CVE-2021-47111 8.8 HIGH xen-netback: take a reference to the RX task thread
CVE-2021-47131 8.1 HIGH net/tls: Fix use-after-free after the TLS device goes down and up
CVE-2021-47135 7.8 HIGH mt76: mt7921: fix possible AOOB issue in mt7921_mcu_tx_rate_report
CVE-2021-47112 7.8 HIGH x86/kvm: Teardown PV features on boot CPU as well
CVE-2021-47129 7.8 HIGH netfilter: nft_ct: skip expectations for confirmed conntrack
CVE-2021-47123 7.8 HIGH io_uring: fix ltout double free on completion race
CVE-2021-47124 7.8 HIGH io_uring: fix link timeout refs
CVE-2021-47126 7.8 HIGH ipv6: Fix KASAN: slab-out-of-bounds Read in fib6_nh_flush_exceptions
CVE-2021-47132 7.5 HIGH mptcp: fix sk_forward_memory corruption on retransmission
CVE-2021-47130 7.5 HIGH nvmet: fix freeing unallocated p2pmem
CVE-2021-47109 7.5 HIGH neighbour: allow NUD_NOARP entries to be forced GCed
CVE-2021-47113 7.1 HIGH btrfs: abort in rename_exchange if we fail to insert the second ref
CVE-2021-47122 net: caif: fix memory leak in caif_device_notify
CVE-2021-47134 efi/fdt: fix panic when no valid fdt found
CVE-2021-47133 HID: amd_sfh: Fix memory leak in amd_sfh_work
CVE-2021-47128 bpf, lockdown, audit: Fix buggy SELinux lockdown permission checks
CVE-2021-47127 ice: track AF_XDP ZC enabled queues in bitmap
CVE-2021-47121 net: caif: fix memory leak in cfusbl_device_notify
CVE-2021-47120 HID: magicmouse: fix NULL-deref on disconnect
CVE-2021-47119 ext4: fix memory leak in ext4_fill_super

Showing top 20 of 26 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2021-47125

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