UBUNTU-CVE-2018-12896

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UBUNTU-CVE-2018-12896

Summary:

Details: An issue was discovered in the Linux kernel through 4.17.3. An Integer Overflow in kernel/time/posix-timers.c in the POSIX timer code is caused by the way the overrun accounting works. Depending on interval and expiry time values, the overrun can be larger than INT_MAX, but the accounting is int based. This basically makes the accounting values, which are visible to user space via timer_getoverrun(2) and siginfo::si_overrun, random. For example, a local user can cause a denial of service (signed integer overflow) via crafted mmap, futex, timer_create, and timer_settime system calls.

References: https://ubuntu.com/security/CVE-2018-12896, https://bugzilla.kernel.org/show_bug.cgi?id=200189, https://github.com/lcytxw/bug_repro/tree/master/bug_200189, https://github.com/torvalds/linux/commit/78c9c4dfbf8c04883941445a195276bb4bb92c76, https://ubuntu.com/security/notices/USN-3847-1, https://ubuntu.com/security/notices/USN-3847-2, https://ubuntu.com/security/notices/USN-3847-3, https://ubuntu.com/security/notices/USN-3848-1, https://ubuntu.com/security/notices/USN-3848-2, https://ubuntu.com/security/notices/USN-3849-1, https://ubuntu.com/security/notices/USN-3849-2, https://www.cve.org/CVERecord?id=CVE-2018-12896