CVE-2025-37984: crypto: ecdsa - Harden against integer overflows in DIV_ROUND_UP()

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-05-20 · updated 2026-10-15
Weakness: CWE-190

Description

In the Linux kernel, the following vulnerability has been resolved: crypto: ecdsa - Harden against integer overflows in DIV_ROUND_UP() Herbert notes that DIV_ROUND_UP() may overflow unnecessarily if an ecdsa implementation's ->key_size() callback returns an unusually large value. Herbert instead suggests (for a division by 8): X / 8 + !!(X & 7) Based on this formula, introduce a generic DIV_ROUND_UP_POW2() macro and use it in lieu of DIV_ROUND_UP() for ->key_size() return values. Additionally, use the macro in ecc_digits_from_bytes(), whose "nbytes" parameter is a ->key_size() return value in some instances, or a user-specified ASN.1 length in the case of ecdsa_get_signature_rs().

Affected products

Linux kernel: from 6.6.70 before 6.6.99; from 6.10 before 6.12.39; from 6.13 before 6.14.5 — fixed in 6.12.39, 6.14.5, 6.6.99

How to fix

Upgrade to a fixed version: Linux kernel 6.12.39, 6.14.5, 6.6.99. Check the vendor advisory for mitigations.

References

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