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CVE-2021-47506— nfsd: fix use-after-free due to delegation race

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，该漏洞源于内存释放后重用。

CVSS 9.8 · Critical EPSS 0.78% · P55

Possible ATT&CK Techniques 1 AI

T1211 · Exploitation for Stealth

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux dff1399f8addf7129c49bb2227469da79cc30b47< 04a8d07f3d58308b92630045560799a3faa3ebce affected
dff1399f8addf7129c49bb2227469da79cc30b47< 348714018139c39533c55661a0c7c990671396b4 affected
dff1399f8addf7129c49bb2227469da79cc30b47< 33645d3e22720cac1e4548f8fef57bf0649536ee affected
dff1399f8addf7129c49bb2227469da79cc30b47< 2becaa990b93cbd2928292c0b669d3abb6cf06d4 affected
dff1399f8addf7129c49bb2227469da79cc30b47< e0759696de6851d7536efddfdd2dfed4c4df1f09 affected
dff1399f8addf7129c49bb2227469da79cc30b47< eeb0711801f5e19ef654371b627682aed3b11373 affected
dff1399f8addf7129c49bb2227469da79cc30b47< 148c816f10fd11df27ca6a9b3238cdd42fa72cd3 affected
dff1399f8addf7129c49bb2227469da79cc30b47< 548ec0805c399c65ed66c6641be467f717833ab5 affected
… +10 more rows
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I. Basic Information for CVE-2021-47506

Vulnerability Information
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Vulnerability Title
nfsd: fix use-after-free due to delegation race
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: nfsd: fix use-after-free due to delegation race A delegation break could arrive as soon as we've called vfs_setlease. A delegation break runs a callback which immediately (in nfsd4_cb_recall_prepare) adds the delegation to del_recall_lru. If we then exit nfs4_set_delegation without hashing the delegation, it will be freed as soon as the callback is done with it, without ever being removed from del_recall_lru. Symptoms show up later as use-after-free or list corruption warnings, usually in the laundromat thread. I suspect aba2072f4523 "nfsd: grant read delegations to clients holding writes" made this bug easier to hit, but I looked as far back as v3.0 and it looks to me it already had the same problem. So I'm not sure where the bug was introduced; it may have been there from the beginning.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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，该漏洞源于内存释放后重用。
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 dff1399f8addf7129c49bb2227469da79cc30b47 ~ 04a8d07f3d58308b92630045560799a3faa3ebce -
Linux Linux 3.17 -

II. Public POCs for CVE-2021-47506

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III. Intelligence Information for CVE-2021-47506

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Other References for CVE-2021-47506 (6)

Same Patch Batch · Linux · 2024-05-24 · 72 CVEs total

CVE-2021-47544 9.8 CRITICAL tcp: fix page frag corruption on page fault
CVE-2021-47536 9.8 CRITICAL net/smc: fix wrong list_del in smc_lgr_cleanup_early
CVE-2021-47520 8.8 HIGH can: pch_can: pch_can_rx_normal: fix use after free
CVE-2021-47561 7.8 HIGH i2c: virtio: disable timeout handling
CVE-2023-52880 7.8 HIGH tty: n_gsm: require CAP_NET_ADMIN to attach N_GSM0710 ldisc
CVE-2021-47502 7.8 HIGH ASoC: codecs: wcd934x: handle channel mappping list correctly
CVE-2021-47505 7.8 HIGH aio: fix use-after-free due to missing POLLFREE handling
CVE-2021-47512 7.8 HIGH net/sched: fq_pie: prevent dismantle issue
CVE-2021-47517 7.8 HIGH ethtool: do not perform operations on net devices being unregistered
CVE-2021-47541 7.8 HIGH net/mlx4_en: Fix an use-after-free bug in mlx4_en_try_alloc_resources()
CVE-2021-47555 7.8 HIGH net: vlan: fix underflow for the real_dev refcnt
CVE-2021-47551 7.8 HIGH drm/amd/amdkfd: Fix kernel panic when reset failed and been triggered again
CVE-2021-47552 7.8 HIGH blk-mq: cancel blk-mq dispatch work in both blk_cleanup_queue and disk_release()
CVE-2021-47533 7.8 HIGH drm/vc4: kms: Clear the HVS FIFO commit pointer once done
CVE-2021-47535 7.8 HIGH drm/msm/a6xx: Allocate enough space for GMU registers
CVE-2021-47500 7.8 HIGH iio: mma8452: Fix trigger reference couting
CVE-2021-47559 7.5 HIGH net/smc: Fix NULL pointer dereferencing in smc_vlan_by_tcpsk()
CVE-2021-47515 7.5 HIGH seg6: fix the iif in the IPv6 socket control block
CVE-2021-47549 sata_fsl: fix UAF in sata_fsl_port_stop when rmmod sata_fsl
CVE-2021-47550 drm/amd/amdgpu: fix potential memleak

Showing top 20 of 72 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2021-47506

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