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

Goal: 1000 CNY · Raised: 1359 CNY

100%
Buy Us a Coffee

CVE-2021-47555— net: vlan: fix underflow for the real_dev refcnt

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real_dev refcnt存在下溢问题。

CVSS 7.8 · High EPSS 0.22% · P12

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 9

VendorProduct Version RangeStatus
Linux Linux 700602b662d7eaa816b1a3cb0abe7a85de358fd4< 5e44178864b38dd70b877985abd7d86fdb95f27d affected
e04a7a84bb77f9cdf4475340fe931389bc72331c< 6e800ee43218a56acc93676bbb3d93b74779e555 affected
21032425c36ff85f16e72ca92193a8c401e4acd5< f7fc72a508cf115c273a7a29350069def1041890 affected
563bcbae3ba233c275c244bfce2efe12938f5363< 01d9cc2dea3fde3bad6d27f464eff463496e2b00 affected
fca96b3f852a1b369b7b2844ce357cd689879934 affected
5.14.19< 5.15 affected
5.4.160< 5.4.163 affected
5.10.80< 5.10.83 affected
… +1 more rows
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2021-47555

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Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.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: vlan: fix underflow for the real_dev refcnt
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: net: vlan: fix underflow for the real_dev refcnt Inject error before dev_hold(real_dev) in register_vlan_dev(), and execute the following testcase: ip link add dev dummy1 type dummy ip link add name dummy1.100 link dummy1 type vlan id 100 ip link del dev dummy1 When the dummy netdevice is removed, we will get a WARNING as following: ======================================================================= refcount_t: decrement hit 0; leaking memory. WARNING: CPU: 2 PID: 0 at lib/refcount.c:31 refcount_warn_saturate+0xbf/0x1e0 and an endless loop of: ======================================================================= unregister_netdevice: waiting for dummy1 to become free. Usage count = -1073741824 That is because dev_put(real_dev) in vlan_dev_free() be called without dev_hold(real_dev) in register_vlan_dev(). It makes the refcnt of real_dev underflow. Move the dev_hold(real_dev) to vlan_dev_init() which is the call-back of ndo_init(). That makes dev_hold() and dev_put() for vlan's real_dev symmetrical.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/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real_dev refcnt存在下溢问题。
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 700602b662d7eaa816b1a3cb0abe7a85de358fd4 ~ 5e44178864b38dd70b877985abd7d86fdb95f27d -
Linux Linux 5.4.160 ~ 5.4.163 -

II. Public POCs for CVE-2021-47555

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

No public POC found.

Login to generate AI POC

III. Intelligence Information for CVE-2021-47555

请登录查看更多情报信息。

Other References for CVE-2021-47555 (4)

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-2021-47506 9.8 CRITICAL nfsd: fix use-after-free due to delegation race
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-2023-52880 7.8 HIGH tty: n_gsm: require CAP_NET_ADMIN to attach N_GSM0710 ldisc
CVE-2021-47512 7.8 HIGH net/sched: fq_pie: prevent dismantle issue
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-2021-47517 7.8 HIGH ethtool: do not perform operations on net devices being unregistered
CVE-2021-47533 7.8 HIGH drm/vc4: kms: Clear the HVS FIFO commit pointer once done
CVE-2021-47500 7.8 HIGH iio: mma8452: Fix trigger reference couting
CVE-2021-47541 7.8 HIGH net/mlx4_en: Fix an use-after-free bug in mlx4_en_try_alloc_resources()
CVE-2021-47552 7.8 HIGH blk-mq: cancel blk-mq dispatch work in both blk_cleanup_queue and disk_release()
CVE-2021-47551 7.8 HIGH drm/amd/amdkfd: Fix kernel panic when reset failed and been triggered again
CVE-2021-47561 7.8 HIGH i2c: virtio: disable timeout handling
CVE-2021-47535 7.8 HIGH drm/msm/a6xx: Allocate enough space for GMU registers
CVE-2021-47515 7.5 HIGH seg6: fix the iif in the IPv6 socket control block
CVE-2021-47559 7.5 HIGH net/smc: Fix NULL pointer dereferencing in smc_vlan_by_tcpsk()
CVE-2021-47513 net: dsa: felix: Fix memory leak in felix_setup_mmio_filtering
CVE-2021-47553 sched/scs: Reset task stack state in bringup_cpu()

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-2021-47555

No comments yet

Leave a comment