CVE-2021-47649: Linux Kernel

Medium severity, CVSS 5.5. EPSS: 0.2% chance of exploitation in the next 30 days.

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().

Affected products

• Linux Linux Kernel: from 4.20, before 5.4.189 (fixed in 5.4.189); from 5.5, before 5.10.110 (fixed in 5.10.110); from 5.11, before 5.15.33 (fixed in 5.15.33); from 5.16, before 5.16.19 (fixed in 5.16.19); from 5.17, before 5.17.2 (fixed in 5.17.2)

Published 2025-02-26. Last modified 2026-06-17.