CVE-2021-47528: linux kernel Null Dereference — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: usb: cdnsp: Fix a NULL pointer dereference in cdnsp_endpoint_init() In cdnsp_endpoint_init(), cdnsp_ring_alloc() is assigned to pep->ring and there is a dereference of it in cdnsp_endpoint_init(), which could lead to a NULL pointer dereference on failure of cdnsp_ring_alloc(). Fix this bug by adding a check of pep->ring. This bug was found by a static analyzer. The analysis employs differential checking to identify inconsistent security operations (e.g., checks or kfrees) between two code paths and confirms that the inconsistent operations are not recovered in the current function or the callers, so they constitute bugs. Note that, as a bug found by static analysis, it can be a false positive or hard to trigger. Multiple researchers have cross-reviewed the bug. Builds with CONFIG_USB_CDNSP_GADGET=y show no new warnings, and our static analyzer no longer warns about this code.

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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	5.12 — 5.15.7

References

Advisories & Patches

https://git.kernel.org/stable/c/37307f7020ab38dde0892a578249bf63d00bca64 https://git.kernel.org/stable/c/7d94bc8e335cb33918e52efdbe192c36707bfa24 https://git.kernel.org/stable/c/37307f7020ab38dde0892a578249bf63d00bca64 https://git.kernel.org/stable/c/7d94bc8e335cb33918e52efdbe192c36707bfa24

Frequently Asked Questions

What is CVE-2021-47528? +

In the Linux kernel, the following vulnerability has been resolved: usb: cdnsp: Fix a NULL pointer dereference in cdnsp_endpoint_init() In cdnsp_endpoint_init(), cdnsp_ring_alloc() is assigned to pep->ring and there is a dereference of it in cdnsp_endpoint_init(), which could lead to a NULL pointer dereference on failure of cdnsp_ring_alloc(). Fix this bug by adding a check of pep->ring. This bug was found by a static analyzer. The analysis employs differential checking to identify inconsistent security operations (e.g., checks or kfrees) between two code paths and confirms that the inconsistent operations are not recovered in the current function or the callers, so they constitute bugs. Note that, as a bug found by static analysis, it can be a false positive or hard to trigger. Multiple researchers have cross-reviewed the bug. Builds with CONFIG_USB_CDNSP_GADGET=y show no new warnings, and our static analyzer no longer warns about this code. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2021-47528? +

CVE-2021-47528 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-2021-47528? +

CVE-2021-47528 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-2021-47528? +

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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