CVE-2019-13272

In the Linux kernel before 5.1.17, ptrace_link in kernel/ptrace.c mishandles the recording of the credentials of a process that wants to create a ptrace relationship, which allows local users to obtain root access by leveraging certain scenarios with a parent-child process relationship, where a parent drops privileges and calls execve (potentially allowing control by an attacker). One contributing factor is an object lifetime issue (which can also cause a panic). Another contributing factor is incorrect marking of a ptrace relationship as privileged, which is exploitable through (for example) Polkits pkexec helper with PTRACE_TRACEME. NOTE: SELinux deny_ptrace might be a usable workaround in some environments.

Affected Software

References

• http://packetstormsecurity.com/files/153663/Linux-PTRACE_TRACEME-Broken-Permission-Object-Lifetime-Handling.html
• http://packetstormsecurity.com/files/153702/Slackware-Security-Advisory-Slackware-14.2-kernel-Updates.html
• http://packetstormsecurity.com/files/154245/Kernel-Live-Patch-Security-Notice-LSN-0054-1.html
• http://packetstormsecurity.com/files/154957/Linux-Polkit-pkexec-Helper-PTRACE_TRACEME-Local-Root.html
• http://packetstormsecurity.com/files/156929/Linux-PTRACE_TRACEME-Local-Root.html
• http://packetstormsecurity.com/files/165051/Linux-Kernel-5.1.x-PTRACE_TRACEME-pkexec-Local-Privilege-Escalation.html
• https://access.redhat.com/errata/RHSA-2019:2405
• https://access.redhat.com/errata/RHSA-2019:2411
• https://access.redhat.com/errata/RHSA-2019:2809
• https://bugs.chromium.org/p/project-zero/issues/detail?id=1903
• https://bugzilla.redhat.com/show_bug.cgi?id=1730895
• https://bugzilla.suse.com/show_bug.cgi?id=1140671
• https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.1.17
• https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=6994eefb0053799d2e07cd140df6c2ea106c41ee
• https://github.com/torvalds/linux/commit/6994eefb0053799d2e07cd140df6c2ea106c41ee
• https://lists.debian.org/debian-lts-announce/2019/07/msg00022.html
• https://lists.debian.org/debian-lts-announce/2019/07/msg00023.html
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/OGRK5LYWBJ4E4SRI4DKX367NHYSI3VOH/
• https://seclists.org/bugtraq/2019/Jul/30
• https://seclists.org/bugtraq/2019/Jul/33
• https://security.netapp.com/advisory/ntap-20190806-0001/
• https://support.f5.com/csp/article/K91025336
• https://support.f5.com/csp/article/K91025336?utm_source=f5support\u0026amp%3Butm_medium=RSS
• https://usn.ubuntu.com/4093-1/
• https://usn.ubuntu.com/4094-1/
• https://usn.ubuntu.com/4095-1/
• https://usn.ubuntu.com/4117-1/
• https://usn.ubuntu.com/4118-1/
• https://www.debian.org/security/2019/dsa-4484