CVE-2020-12656

Published: 5 May 2020

** DISPUTED ** gss_mech_free in net/sunrpc/auth_gss/gss_mech_switch.c in the rpcsec_gss_krb5 implementation in the Linux kernel through 5.6.10 lacks certain domain_release calls, leading to a memory leak. Note: This was disputed with the assertion that the issue does not grant any access not already available. It is a problem that on unloading a specific kernel module some memory is leaked, but loading kernel modules is a privileged operation. A user could also write a kernel module to consume any amount of memory they like and load that replicating the effect of this bug.

From the Ubuntu Security Team

It was discovered that the Kerberos SUNRPC GSS implementation in the Linux kernel did not properly deallocate memory on module unload. A local privileged attacker could possibly use this to cause a denial of service (memory exhaustion).

Notes

upstream generally treats module unload as an unsafe
operation, which may explain a lack of progress in addressing the
issue.

Status

Severity score breakdown

References

• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-12656
• https://bugzilla.kernel.org/show_bug.cgi?id=206651
• https://ubuntu.com/security/notices/USN-4483-1
• https://ubuntu.com/security/notices/USN-4485-1
• NVD
• Launchpad
• Debian