CVE-2021-47223

MEDIUM
Published May 21, 2024 Modified Feb 3, 2025 CWE-476

Description

In the Linux kernel, the following vulnerability has been resolved: net: bridge: fix vlan tunnel dst null pointer dereference This patch fixes a tunnel_dst null pointer dereference due to lockless access in the tunnel egress path. When deleting a vlan tunnel the tunnel_dst pointer is set to NULL without waiting a grace period (i.e. while it's still usable) and packets egressing are dereferencing it without checking. Use READ/WRITE_ONCE to annotate the lockless use of tunnel_id, use RCU for accessing tunnel_dst and make sure it is read only once and checked in the egress path. The dst is already properly RCU protected so we don't need to do anything fancy than to make sure tunnel_id and tunnel_dst are read only once and checked in the egress path.

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CVSS v3.1 Score

5.5
MEDIUM
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-476 CWE-476

Affected Products

Vendor Product
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel

References

Advisories & Patches

https://git.kernel.org/stable/c/24a6e55f17aa123bc1fc54b7d3c410b41bc16530 https://git.kernel.org/stable/c/58e2071742e38f29f051b709a5cca014ba51166f https://git.kernel.org/stable/c/a2241e62f6b4a774d8a92048fdf59c45f6c2fe5c https://git.kernel.org/stable/c/abb02e05cb1c0a30dd873a29f33bc092067dc35d https://git.kernel.org/stable/c/ad7feefe7164892db424c45687472db803d87f79 https://git.kernel.org/stable/c/fe0448a3fad365a747283a00a1d1ad5e8d6675b7 https://git.kernel.org/stable/c/24a6e55f17aa123bc1fc54b7d3c410b41bc16530 https://git.kernel.org/stable/c/58e2071742e38f29f051b709a5cca014ba51166f https://git.kernel.org/stable/c/a2241e62f6b4a774d8a92048fdf59c45f6c2fe5c https://git.kernel.org/stable/c/abb02e05cb1c0a30dd873a29f33bc092067dc35d https://git.kernel.org/stable/c/ad7feefe7164892db424c45687472db803d87f79 https://git.kernel.org/stable/c/fe0448a3fad365a747283a00a1d1ad5e8d6675b7

Frequently Asked Questions

What is CVE-2021-47223? +
In the Linux kernel, the following vulnerability has been resolved: net: bridge: fix vlan tunnel dst null pointer dereference This patch fixes a tunnel_dst null pointer dereference due to lockless access in the tunnel egress path. When deleting a vlan tunnel the tunnel_dst pointer is set to NULL without waiting a grace period (i.e. while it's still usable) and packets egressing are dereferencing it without checking. Use READ/WRITE_ONCE to annotate the lockless use of tunnel_id, use RCU for accessing tunnel_dst and make sure it is read only once and checked in the egress path. The dst is already properly RCU protected so we don't need to do anything fancy than to make sure tunnel_id and tunnel_dst are read only once and checked in the egress path. It has a CVSS v3.1 base score of 5.5 (MEDIUM).
How severe is CVE-2021-47223? +
CVE-2021-47223 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.
What products are affected by CVE-2021-47223? +
CVE-2021-47223 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.
How do I check if I'm vulnerable to CVE-2021-47223? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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