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CVE-2021-47584— iocost: Fix divide-by-zero on donation from low hweight cgroup

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，该漏洞源于允许存在除以零问题。

AI Predicted 5.5 Difficulty: Moderate EPSS 0.25% · P15

Possible ATT&CK Techniques 1 AI

T1059 · Command and Scripting Interpreter

Affected Version Matrix 8

VendorProduct Version RangeStatus
Linux Linux f1de2439ec43b74764f2a26e3a310b24407e3bde< a7c80674538f15f85d68138240aae440b8039519 affected
f1de2439ec43b74764f2a26e3a310b24407e3bde< 3a1a4eb574178c21241a6200f4785572e661c472 affected
f1de2439ec43b74764f2a26e3a310b24407e3bde< edaa26334c117a584add6053f48d63a988d25a6e affected
5.10 affected
< 5.10 unaffected
5.10.88≤ 5.10.* unaffected
5.15.11≤ 5.15.* unaffected
5.16≤ * unaffected
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I. Basic Information for CVE-2021-47584

Vulnerability Information
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Vulnerability Title
iocost: Fix divide-by-zero on donation from low hweight cgroup
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: iocost: Fix divide-by-zero on donation from low hweight cgroup The donation calculation logic assumes that the donor has non-zero after-donation hweight, so the lowest active hweight a donating cgroup can have is 2 so that it can donate 1 while keeping the other 1 for itself. Earlier, we only donated from cgroups with sizable surpluses so this condition was always true. However, with the precise donation algorithm implemented, f1de2439ec43 ("blk-iocost: revamp donation amount determination") made the donation amount calculation exact enabling even low hweight cgroups to donate. This means that in rare occasions, a cgroup with active hweight of 1 can enter donation calculation triggering the following warning and then a divide-by-zero oops. WARNING: CPU: 4 PID: 0 at block/blk-iocost.c:1928 transfer_surpluses.cold+0x0/0x53 [884/94867] ... RIP: 0010:transfer_surpluses.cold+0x0/0x53 Code: 92 ff 48 c7 c7 28 d1 ab b5 65 48 8b 34 25 00 ae 01 00 48 81 c6 90 06 00 00 e8 8b 3f fe ff 48 c7 c0 ea ff ff ff e9 95 ff 92 ff <0f> 0b 48 c7 c7 30 da ab b5 e8 71 3f fe ff 4c 89 e8 4d 85 ed 74 0 4 ... Call Trace: <IRQ> ioc_timer_fn+0x1043/0x1390 call_timer_fn+0xa1/0x2c0 __run_timers.part.0+0x1ec/0x2e0 run_timer_softirq+0x35/0x70 ... iocg: invalid donation weights in /a/b: active=1 donating=1 after=0 Fix it by excluding cgroups w/ active hweight < 2 from donating. Excluding these extreme low hweight donations shouldn't affect work conservation in any meaningful way.
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，该漏洞源于允许存在除以零问题。
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 f1de2439ec43b74764f2a26e3a310b24407e3bde ~ a7c80674538f15f85d68138240aae440b8039519 -
Linux Linux 5.10 -

II. Public POCs for CVE-2021-47584

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III. Intelligence Information for CVE-2021-47584

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Other References for CVE-2021-47584 (3)

Same Patch Batch · Linux · 2024-06-19 · 122 CVEs total

CVE-2024-38558 10.0 CRITICAL net: openvswitch: fix overwriting ct original tuple for ICMPv6
CVE-2024-38570 9.8 CRITICAL gfs2: Fix potential glock use-after-free on unmount
CVE-2021-47587 9.8 CRITICAL net: systemport: Add global locking for descriptor lifecycle
CVE-2024-38544 9.8 CRITICAL RDMA/rxe: Fix seg fault in rxe_comp_queue_pkt
CVE-2021-47611 8.1 HIGH mac80211: validate extended element ID is present
CVE-2024-38587 7.8 HIGH speakup: Fix sizeof() vs ARRAY_SIZE() bug
CVE-2024-38556 7.8 HIGH net/mlx5: Add a timeout to acquire the command queue semaphore
CVE-2024-38610 7.8 HIGH drivers/virt/acrn: fix PFNMAP PTE checks in acrn_vm_ram_map()
CVE-2024-38605 7.8 HIGH ALSA: core: Fix NULL module pointer assignment at card init
CVE-2024-38599 7.8 HIGH jffs2: prevent xattr node from overflowing the eraseblock
CVE-2024-38592 7.8 HIGH drm/mediatek: Init `ddp_comp` with devm_kcalloc()
CVE-2024-38564 7.8 HIGH bpf: Add BPF_PROG_TYPE_CGROUP_SKB attach type enforcement in BPF_LINK_CREATE
CVE-2024-38568 7.8 HIGH drivers/perf: hisi: hns3: Fix out-of-bound access when valid event group
CVE-2024-38572 7.8 HIGH wifi: ath12k: fix out-of-bound access of qmi_invoke_handler()
CVE-2024-38578 7.8 HIGH ecryptfs: Fix buffer size for tag 66 packet
CVE-2024-38580 7.8 HIGH epoll: be better about file lifetimes
CVE-2024-38569 7.8 HIGH drivers/perf: hisi_pcie: Fix out-of-bound access when valid event group
CVE-2024-38583 7.8 HIGH nilfs2: fix use-after-free of timer for log writer thread
CVE-2024-38614 7.8 HIGH openrisc: traps: Don't send signals to kernel mode threads
CVE-2024-38588 7.8 HIGH ftrace: Fix possible use-after-free issue in ftrace_location()

Showing top 20 of 122 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2021-47584

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