CVE-2021-47649: linux kernel — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: udmabuf: validate ubuf->pagecount Syzbot has reported GPF in sg_alloc_append_table_from_pages(). The problem was in ubuf->pages == ZERO_PTR. ubuf->pagecount is calculated from arguments passed from user-space. If user creates udmabuf with list.size == 0 then ubuf->pagecount will be also equal to zero; it causes kmalloc_array() to return ZERO_PTR. Fix it by validating ubuf->pagecount before passing it to kmalloc_array().

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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

Affected Products

Vendor	Product	Versions
linux	linux_kernel	4.20 — 5.4.189
linux	linux_kernel	5.5 — 5.10.110
linux	linux_kernel	5.11 — 5.15.33
linux	linux_kernel	5.16 — 5.16.19
linux	linux_kernel	5.17 — 5.17.2

References

Advisories & Patches

https://git.kernel.org/stable/c/2b6dd600dd72573c23ea180b5b0b2f1813405882 https://git.kernel.org/stable/c/5d50f851dd307c07ca5591297093f19967c834a9 https://git.kernel.org/stable/c/811b667cefbea9cb7511a874b169d6a92907137e https://git.kernel.org/stable/c/9e9b4a269f84d3230f2af84ff42322db676440d9 https://git.kernel.org/stable/c/a3728d32fc61eb0fe283cb8ff60b2c8f751e2202 https://git.kernel.org/stable/c/b267a8118c2b171bf7d67b90ed64154eeab9fae0

Frequently Asked Questions

What is CVE-2021-47649? +

In the Linux kernel, the following vulnerability has been resolved: udmabuf: validate ubuf->pagecount Syzbot has reported GPF in sg_alloc_append_table_from_pages(). The problem was in ubuf->pages == ZERO_PTR. ubuf->pagecount is calculated from arguments passed from user-space. If user creates udmabuf with list.size == 0 then ubuf->pagecount will be also equal to zero; it causes kmalloc_array() to return ZERO_PTR. Fix it by validating ubuf->pagecount before passing it to kmalloc_array(). It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2021-47649? +

CVE-2021-47649 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-2021-47649? +

CVE-2021-47649 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-2021-47649? +

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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CVE-2021-47649