What’s Vulnerable › Vulnerabilities

CVE-2021-47040: io_uring: fix overflows checks in provide buffers

• Severity: high (CVSS 7.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2024-02-28 · updated 2026-08-04
• Weakness: CWE-120

Description

In the Linux kernel, the following vulnerability has been resolved: io_uring: fix overflows checks in provide buffers Colin reported before possible overflow and sign extension problems in io_provide_buffers_prep(). As Linus pointed out previous attempt did nothing useful, see d81269fecb8ce ("io_uring: fix provide_buffers sign extension"). Do that with help of check_<op>_overflow helpers. And fix struct io_provide_buf::len type, as it doesn't make much sense to keep it signed.

Affected products

• Linux kernel: from 5.8 before 5.10.37; from 5.11 before 5.11.21; from 5.12 before 5.12.4 — fixed in 5.10.37, 5.11.21, 5.12.4

How to fix

Upgrade to a fixed version: Linux kernel 5.10.37, 5.11.21, 5.12.4. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/38134ada0ceea3e848fe993263c0ff6207fd46e7
• https://git.kernel.org/stable/c/51bf90901952aaac564bbdb36b2b503050c53dd9
• https://git.kernel.org/stable/c/84b8c266c4bfe9ed5128e13253c388deb74b1b03
• https://git.kernel.org/stable/c/cbbc13b115b8f18e0a714d89f87fbdc499acfe2d
• https://git.kernel.org/stable/c/38134ada0ceea3e848fe993263c0ff6207fd46e7
• https://git.kernel.org/stable/c/51bf90901952aaac564bbdb36b2b503050c53dd9
• https://git.kernel.org/stable/c/84b8c266c4bfe9ed5128e13253c388deb74b1b03
• https://git.kernel.org/stable/c/cbbc13b115b8f18e0a714d89f87fbdc499acfe2d

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