CVE-2022-50063
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-06-18

Last updated on: 2025-11-13

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: net: dsa: felix: suppress non-changes to the tagging protocol The way in which dsa_tree_change_tag_proto() works is that when dsa_tree_notify() fails, it doesn't know whether the operation failed mid way in a multi-switch tree, or it failed for a single-switch tree. So even though drivers need to fail cleanly in ds->ops->change_tag_protocol(), DSA will still call dsa_tree_notify() again, to restore the old tag protocol for potential switches in the tree where the change did succeeed (before failing for others). This means for the felix driver that if we report an error in felix_change_tag_protocol(), we'll get another call where proto_ops == old_proto_ops. If we proceed to act upon that, we may do unexpected things. For example, we will call dsa_tag_8021q_register() twice in a row, without any dsa_tag_8021q_unregister() in between. Then we will actually call dsa_tag_8021q_unregister() via old_proto_ops->teardown, which (if it manages to run at all, after walking through corrupted data structures) will leave the ports inoperational anyway. The bug can be readily reproduced if we force an error while in tag_8021q mode; this crashes the kernel. echo ocelot-8021q > /sys/class/net/eno2/dsa/tagging echo edsa > /sys/class/net/eno2/dsa/tagging # -EPROTONOSUPPORT Unable to handle kernel NULL pointer dereference at virtual address 0000000000000014 Call trace: vcap_entry_get+0x24/0x124 ocelot_vcap_filter_del+0x198/0x270 felix_tag_8021q_vlan_del+0xd4/0x21c dsa_switch_tag_8021q_vlan_del+0x168/0x2cc dsa_switch_event+0x68/0x1170 dsa_tree_notify+0x14/0x34 dsa_port_tag_8021q_vlan_del+0x84/0x110 dsa_tag_8021q_unregister+0x15c/0x1c0 felix_tag_8021q_teardown+0x16c/0x180 felix_change_tag_protocol+0x1bc/0x230 dsa_switch_event+0x14c/0x1170 dsa_tree_change_tag_proto+0x118/0x1c0
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Meta Information
Published
2025-06-18
Last Modified
2025-11-13
Generated
2026-05-07
AI Q&A
2025-06-18
EPSS Evaluated
2026-05-05
NVD
CVE-2022-50063
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel From 5.15.160 (inc) to 5.16 (inc)
Helpful Resources
Exploitability
CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-476 The product dereferences a pointer that it expects to be valid but is NULL.
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability is in the Linux kernel's DSA (Distributed Switch Architecture) felix driver. When changing the tagging protocol, if an error occurs, the system may incorrectly attempt to restore the old protocol by calling certain functions multiple times without proper cleanup. This can lead to corrupted data structures and ultimately cause a kernel crash due to a NULL pointer dereference.


How can this vulnerability impact me? :

The vulnerability can cause the Linux kernel to crash, leading to system instability or downtime. Specifically, it can leave network ports inoperational and cause a kernel NULL pointer dereference, which may disrupt network functionality on affected systems.


How can this vulnerability be detected on my network or system? Can you suggest some commands?

This vulnerability can be detected by attempting to reproduce the error condition described, specifically by forcing an error while in tag_8021q mode on the affected network interface. The example commands to trigger the issue are: 1. echo ocelot-8021q > /sys/class/net/eno2/dsa/tagging 2. echo edsa > /sys/class/net/eno2/dsa/tagging # This should return -EPROTONOSUPPORT error If the kernel crashes or logs a NULL pointer dereference related to felix_change_tag_protocol or dsa_tag_8021q_unregister, it indicates the presence of the vulnerability.


What immediate steps should I take to mitigate this vulnerability?

Immediate mitigation steps include avoiding forcing errors in tag_8021q mode on devices using the felix driver and ensuring that the Linux kernel is updated to a version where this vulnerability is fixed. Since the issue arises from improper handling of tag protocol changes in the felix driver, applying the patch that suppresses non-changes to the tagging protocol will prevent kernel crashes and port inoperability.


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