CVE - CVE-2025-21920

CVE-ID
CVE-2025-21920	Learn more at National Vulnerability Database (NVD) • CVSS Severity Rating • Fix Information • Vulnerable Software Versions • SCAP Mappings • CPE Information
Description
In the Linux kernel, the following vulnerability has been resolved: vlan: enforce underlying device type Currently, VLAN devices can be created on top of non-ethernet devices. Besides the fact that it doesn't make much sense, this also causes a bug which leaks the address of a kernel function to usermode. When creating a VLAN device, we initialize GARP (garp_init_applicant) and MRP (mrp_init_applicant) for the underlying device. As part of the initialization process, we add the multicast address of each applicant to the underlying device, by calling dev_mc_add. __dev_mc_add uses dev->addr_len to determine the length of the new multicast address. This causes an out-of-bounds read if dev->addr_len is greater than 6, since the multicast addresses provided by GARP and MRP are only 6 bytes long. This behaviour can be reproduced using the following commands: ip tunnel add gretest mode ip6gre local ::1 remote ::2 dev lo ip l set up dev gretest ip link add link gretest name vlantest type vlan id 100 Then, the following command will display the address of garp_pdu_rcv: ip maddr show \| grep 01:80:c2:00:00:21 Fix the bug by enforcing the type of the underlying device during VLAN device initialization.
References
Note: References are provided for the convenience of the reader to help distinguish between vulnerabilities. The list is not intended to be complete.
MISC:https://git.kernel.org/stable/c/0fb7aa04c19eac4417f360a9f7611a60637bdacc URL:https://git.kernel.org/stable/c/0fb7aa04c19eac4417f360a9f7611a60637bdacc MISC:https://git.kernel.org/stable/c/30e8aee77899173a82ae5ed89f536c096f20aaeb URL:https://git.kernel.org/stable/c/30e8aee77899173a82ae5ed89f536c096f20aaeb MISC:https://git.kernel.org/stable/c/3561442599804905c3defca241787cd4546e99a7 URL:https://git.kernel.org/stable/c/3561442599804905c3defca241787cd4546e99a7 MISC:https://git.kernel.org/stable/c/5a515d13e15536e82c5c7c83eb6cf5bc4827fee5 URL:https://git.kernel.org/stable/c/5a515d13e15536e82c5c7c83eb6cf5bc4827fee5 MISC:https://git.kernel.org/stable/c/7f1564b2b2072b7aa1ac75350e9560a07c7a44fd URL:https://git.kernel.org/stable/c/7f1564b2b2072b7aa1ac75350e9560a07c7a44fd MISC:https://git.kernel.org/stable/c/b33a534610067ade2bdaf2052900aaad99701353 URL:https://git.kernel.org/stable/c/b33a534610067ade2bdaf2052900aaad99701353 MISC:https://git.kernel.org/stable/c/b6c72479748b7ea09f53ed64b223cee6463dc278 URL:https://git.kernel.org/stable/c/b6c72479748b7ea09f53ed64b223cee6463dc278 MISC:https://git.kernel.org/stable/c/fa40ebef69234e39ec2d26930d045f2fb9a8cb2b URL:https://git.kernel.org/stable/c/fa40ebef69234e39ec2d26930d045f2fb9a8cb2b
Assigning CNA
kernel.org
Date Record Created
20241229	Disclaimer: The record creation date may reflect when the CVE ID was allocated or reserved, and does not necessarily indicate when this vulnerability was discovered, shared with the affected vendor, publicly disclosed, or updated in CVE.
Phase (Legacy)
Assigned (20241229)
Votes (Legacy)

Comments (Legacy)

Proposed (Legacy)
N/A
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