CVE-2021-47555
Linux Vlan Refcount Underflow 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.
INFO
Published Date :
May 24, 2024, 3:15 p.m.
Last Modified :
Nov. 21, 2024, 6:36 a.m.
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Remotely Exploitable :
No
Impact Score :
2.5
Exploitability Score :
1.8
References to Advisories, Solutions, and Tools
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CVE-2021-47555.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
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The following list is the news that have been mention
CVE-2021-47555 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2021-47555 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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CVE Modified by af854a3a-2127-422b-91ae-364da2661108
Nov. 21, 2024
Action Type Old Value New Value Added Reference https://git.kernel.org/stable/c/01d9cc2dea3fde3bad6d27f464eff463496e2b00 Added Reference https://git.kernel.org/stable/c/5e44178864b38dd70b877985abd7d86fdb95f27d Added Reference https://git.kernel.org/stable/c/6e800ee43218a56acc93676bbb3d93b74779e555 Added Reference https://git.kernel.org/stable/c/f7fc72a508cf115c273a7a29350069def1041890 -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Nov. 04, 2024
Action Type Old Value New Value Added CVSS V3.1 CISA-ADP AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:L -
CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
May. 28, 2024
Action Type Old Value New Value -
CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
May. 24, 2024
Action Type Old Value New Value Added 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. Added Reference kernel.org https://git.kernel.org/stable/c/5e44178864b38dd70b877985abd7d86fdb95f27d [No types assigned] Added Reference kernel.org https://git.kernel.org/stable/c/6e800ee43218a56acc93676bbb3d93b74779e555 [No types assigned] Added Reference kernel.org https://git.kernel.org/stable/c/f7fc72a508cf115c273a7a29350069def1041890 [No types assigned] Added Reference kernel.org https://git.kernel.org/stable/c/01d9cc2dea3fde3bad6d27f464eff463496e2b00 [No types assigned]
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2021-47555 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2021-47555
weaknesses.