CVE-2021-4441: linux kernel Null Dereference — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: spi: spi-zynq-qspi: Fix a NULL pointer dereference in zynq_qspi_exec_mem_op() In zynq_qspi_exec_mem_op(), kzalloc() is directly used in memset(), which could lead to a NULL pointer dereference on failure of kzalloc(). Fix this bug by adding a check of tmpbuf. 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_SPI_ZYNQ_QSPI=m 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	5.2 — 5.4.182
linux	linux_kernel	5.5 — 5.10.103
linux	linux_kernel	5.11 — 5.15.26
linux	linux_kernel	5.16 — 5.16.12
linux	linux_kernel	All
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/2efece1368aeee2d2552c7ec36aeb676c4d4c95f https://git.kernel.org/stable/c/3c32405d6474a21f7d742828e73c13e326dcae82 https://git.kernel.org/stable/c/ab3824427b848da10e9fe2727f035bbeecae6ff4 https://git.kernel.org/stable/c/b9dd08cbebe0c593c49bf86d2012a431494e54cb https://git.kernel.org/stable/c/df14d2bed8e2455878e046e67123d9ecb2e79056

Frequently Asked Questions

What is CVE-2021-4441? +

In the Linux kernel, the following vulnerability has been resolved: spi: spi-zynq-qspi: Fix a NULL pointer dereference in zynq_qspi_exec_mem_op() In zynq_qspi_exec_mem_op(), kzalloc() is directly used in memset(), which could lead to a NULL pointer dereference on failure of kzalloc(). Fix this bug by adding a check of tmpbuf. 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_SPI_ZYNQ_QSPI=m 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-2021-4441? +

CVE-2021-4441 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-2021-4441? +

CVE-2021-4441 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-2021-4441? +

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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