CVE-2021-47312: linux kernel Null Dereference — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: Fix dereference of null pointer flow In the case where chain->flags & NFT_CHAIN_HW_OFFLOAD is false then nft_flow_rule_create is not called and flow is NULL. The subsequent error handling execution via label err_destroy_flow_rule will lead to a null pointer dereference on flow when calling nft_flow_rule_destroy. Since the error path to err_destroy_flow_rule has to cater for null and non-null flows, only call nft_flow_rule_destroy if flow is non-null to fix this issue. Addresses-Coverity: ("Explicity null dereference")

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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	Versions
linux	linux_kernel	5.13.2 — 5.13.5

References

Advisories & Patches

https://git.kernel.org/stable/c/4ca041f919f13783b0b03894783deee00dbca19a https://git.kernel.org/stable/c/70a5a1950cca02c5cd161bb3846b4d983eed97d3 https://git.kernel.org/stable/c/4ca041f919f13783b0b03894783deee00dbca19a https://git.kernel.org/stable/c/70a5a1950cca02c5cd161bb3846b4d983eed97d3

Frequently Asked Questions

What is CVE-2021-47312? +

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: Fix dereference of null pointer flow In the case where chain->flags & NFT_CHAIN_HW_OFFLOAD is false then nft_flow_rule_create is not called and flow is NULL. The subsequent error handling execution via label err_destroy_flow_rule will lead to a null pointer dereference on flow when calling nft_flow_rule_destroy. Since the error path to err_destroy_flow_rule has to cater for null and non-null flows, only call nft_flow_rule_destroy if flow is non-null to fix this issue. Addresses-Coverity: ("Explicity null dereference") It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2021-47312? +

CVE-2021-47312 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-2021-47312? +

CVE-2021-47312 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-2021-47312? +

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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