CVE-2021-47649

low-risk
Published 2025-02-26

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().

Do I need to act?

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0.01% chance of exploitation
EPSS score — low exploit probability
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Not on CISA KEV list
No confirmed active exploitation reported to CISA
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Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
5
CVSS 5.5/10 Medium
LOCAL / LOW complexity

Affected Products (1)

Affected Vendors

Linux

References (6)

Patch https://git.kernel.org/stable/c/2b6dd600dd72573c23ea180b5b0b2f1813405882
Patch https://git.kernel.org/stable/c/5d50f851dd307c07ca5591297093f19967c834a9
Patch https://git.kernel.org/stable/c/811b667cefbea9cb7511a874b169d6a92907137e
Patch https://git.kernel.org/stable/c/9e9b4a269f84d3230f2af84ff42322db676440d9
Patch https://git.kernel.org/stable/c/a3728d32fc61eb0fe283cb8ff60b2c8f751e2202
Patch https://git.kernel.org/stable/c/b267a8118c2b171bf7d67b90ed64154eeab9fae0
23
/ 100
low-risk
Severity 18/34 · Moderate
Exploitability 0/34 · Minimal
Exposure 5/34 · Minimal