CVE-2020-28941

An issue was discovered in drivers/accessibility/speakup/spk_ttyio.c in the Linux kernel through 5.9.9. Local attackers on systems with the speakup driver could cause a local denial of service attack, aka CID-d41227544427. This occurs because of an invalid free when the line discipline is used more than once.

Weakness

The product attempts to return a memory resource to the system, but it calls the wrong release function or calls the appropriate release function incorrectly.

Affected Software

Extended Description

This weakness can take several forms, such as:

Potential Mitigations

• Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
• For example, glibc in Linux provides protection against free of invalid pointers.

References

• http://www.openwall.com/lists/oss-security/2020/11/19/5
• https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=d4122754442799187d5d537a9c039a49a67e57f1
• https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git/commit/?h=tty-linus\u0026id=d4122754442799187d5d537a9c039a49a67e57f1
• https://github.com/torvalds/linux/commit/d4122754442799187d5d537a9c039a49a67e57f1
• https://lists.debian.org/debian-lts-announce/2020/12/msg00015.html
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TITJQPYDWZ4NB2ONJWUXW75KSQIPF35T/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZF4OGZPKTAJJXWHPIFP3LHEWWEMR5LPT/
• https://www.openwall.com/lists/oss-security/2020/11/19/3