In the Linux kernel, a certain net/ipv4/tcp_output.c change, which was...

Vulnerability Description

In the Linux kernel, a certain net/ipv4/tcp_output.c change, which was properly incorporated into 4.16.12, was incorrectly backported to the earlier longterm kernels, introducing a new vulnerability that was potentially more severe than the issue that was intended to be fixed by backporting. Specifically, by adding to a write queue between disconnection and re-connection, a local attacker can trigger multiple use-after-free conditions. This can result in a kernel crash, or potentially in privilege escalation. NOTE: this affects (for example) Linux distributions that use 4.9.x longterm kernels before 4.9.190 or 4.14.x longterm kernels before 4.14.139.

References

• https://pulsesecurity.co.nz/advisories/linux-kernel-4.9-tcpsocketsuaf
• https://www.debian.org/security/2019/dsa-4497
• https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7f582b248d0a86bae5788c548d7bb5bca6f7691a
• https://lore.kernel.org/stable/41a61a2f87691d2bc839f26cdfe6f5ff2f51e472.camel%40decadent.org.uk/
• https://salsa.debian.org/kernel-team/kernel-sec/blob/f6273af2d956a87296b6b60379d0a186c9be4bbc/active/CVE-2019-15239
• http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00064.html
• http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00066.html
• https://access.redhat.com/errata/RHSA-2019:3978
• https://access.redhat.com/errata/RHSA-2019:3979
• https://access.redhat.com/errata/RHSA-2020:0027