CVE-2021-47427: linux kernel Use-After-Free — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: scsi: iscsi: Fix iscsi_task use after free Commit d39df158518c ("scsi: iscsi: Have abort handler get ref to conn") added iscsi_get_conn()/iscsi_put_conn() calls during abort handling but then also changed the handling of the case where we detect an already completed task where we now end up doing a goto to the common put/cleanup code. This results in a iscsi_task use after free, because the common cleanup code will do a put on the iscsi_task. This reverts the goto and moves the iscsi_get_conn() to after we've checked if the iscsi_task is valid.

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CVSS v3.1 Score

7.8

HIGH

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

Weakness Type (CWE)

CWE-416 Use After Free

Affected Products

Vendor	Product	Versions
linux	linux_kernel	5.14 — 5.14.12
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All

References

Advisories & Patches

https://git.kernel.org/stable/c/1642f51ac0d4f2b55d5748094c49ff8f7191b93c https://git.kernel.org/stable/c/258aad75c62146453d03028a44f2f1590d58e1f6 https://git.kernel.org/stable/c/1642f51ac0d4f2b55d5748094c49ff8f7191b93c https://git.kernel.org/stable/c/258aad75c62146453d03028a44f2f1590d58e1f6

Frequently Asked Questions

What is CVE-2021-47427? +

In the Linux kernel, the following vulnerability has been resolved: scsi: iscsi: Fix iscsi_task use after free Commit d39df158518c ("scsi: iscsi: Have abort handler get ref to conn") added iscsi_get_conn()/iscsi_put_conn() calls during abort handling but then also changed the handling of the case where we detect an already completed task where we now end up doing a goto to the common put/cleanup code. This results in a iscsi_task use after free, because the common cleanup code will do a put on the iscsi_task. This reverts the goto and moves the iscsi_get_conn() to after we've checked if the iscsi_task is valid. It has a CVSS v3.1 base score of 7.8 (HIGH).

How severe is CVE-2021-47427? +

CVE-2021-47427 has a CVSS v3.1 score of 7.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

What products are affected by CVE-2021-47427? +

CVE-2021-47427 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-2021-47427? +

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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