15

May

by pi3

CVE-2020-12826 is assigned to track the problem with Linux kernel which I’ve described in my previous post:

CVE MITRE described the problem pretty accurately:

A signal access-control issue was discovered in the Linux kernel before 5.6.5, aka CID-7395ea4e65c2. Because exec_id in include/linux/sched.h is only 32 bits, an integer overflow can interfere with a do_notify_parent protection mechanism. A child process can send an arbitrary signal to a parent process in a different security domain. Exploitation limitations include the amount of elapsed time before an integer overflow occurs, and the lack of scenarios where signals to a parent process present a substantial operational threat.

RedHat tracks this issue here:

https://bugzilla.redhat.com/show_bug.cgi?id=1822077

Debian here:

https://security-tracker.debian.org/tracker/CVE-2020-12826

Fix can be found here:

https://github.com/torvalds/linux/commit/7395ea4e65c2a00d23185a3f63ad315756ba9cef

What is interesting, the story of insufficient restriction of the exit signals might not be ended 😉

In short, the following patch reintroduces the same problem:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b5f2006144c6ae941726037120fa1001ddede784

Best regards,
Adam