UBUNTU-CVE-2019-15239

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UBUNTU-CVE-2019-15239

Summary:

Details: 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://ubuntu.com/security/CVE-2019-15239, https://pulsesecurity.co.nz/advisories/linux-kernel-4.9-tcpsocketsuaf, https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7f582b248d0a86bae5788c548d7bb5bca6f7691a, https://lore.kernel.org/stable/[email protected]/, https://salsa.debian.org/kernel-team/kernel-sec/blob/f6273af2d956a87296b6b60379d0a186c9be4bbc/active/CVE-2019-15239, https://www.debian.org/security/2019/dsa-4497, https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/xenial/commit/?id=edff0f7fc52aa3fba1141755ae5aa008c51eb518, https://www.cve.org/CVERecord?id=CVE-2019-15239