CVE-2021-47183: linux kernel Null Dereference — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: scsi: lpfc: Fix link down processing to address NULL pointer dereference If an FC link down transition while PLOGIs are outstanding to fabric well known addresses, outstanding ABTS requests may result in a NULL pointer dereference. Driver unload requests may hang with repeated "2878" log messages. The Link down processing results in ABTS requests for outstanding ELS requests. The Abort WQEs are sent for the ELSs before the driver had set the link state to down. Thus the driver is sending the Abort with the expectation that an ABTS will be sent on the wire. The Abort request is stalled waiting for the link to come up. In some conditions the driver may auto-complete the ELSs thus if the link does come up, the Abort completions may reference an invalid structure. Fix by ensuring that Abort set the flag to avoid link traffic if issued due to conditions where the link failed.

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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	< 5.15.5

References

Advisories & Patches

https://git.kernel.org/stable/c/1854f53ccd88ad4e7568ddfafafffe71f1ceb0a6 https://git.kernel.org/stable/c/28de48a7cea495ab48082d9ff4ef63f7cb4e563a https://git.kernel.org/stable/c/1854f53ccd88ad4e7568ddfafafffe71f1ceb0a6 https://git.kernel.org/stable/c/28de48a7cea495ab48082d9ff4ef63f7cb4e563a

Other References

https://git.kernel.org/stable/c/04c1af683270e4709a594bb1691b8800b945035a https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html

Frequently Asked Questions

What is CVE-2021-47183? +

In the Linux kernel, the following vulnerability has been resolved: scsi: lpfc: Fix link down processing to address NULL pointer dereference If an FC link down transition while PLOGIs are outstanding to fabric well known addresses, outstanding ABTS requests may result in a NULL pointer dereference. Driver unload requests may hang with repeated "2878" log messages. The Link down processing results in ABTS requests for outstanding ELS requests. The Abort WQEs are sent for the ELSs before the driver had set the link state to down. Thus the driver is sending the Abort with the expectation that an ABTS will be sent on the wire. The Abort request is stalled waiting for the link to come up. In some conditions the driver may auto-complete the ELSs thus if the link does come up, the Abort completions may reference an invalid structure. Fix by ensuring that Abort set the flag to avoid link traffic if issued due to conditions where the link failed. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2021-47183? +

CVE-2021-47183 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-2021-47183? +

CVE-2021-47183 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-2021-47183? +

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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