Date: Wed, 9 Jul 2014 10:38:13 +0400 From: Solar Designer <solar@...nwall.com> To: oss-security@...ts.openwall.com Subject: Re: CVE-2014-4699: Linux ptrace bug On Tue, Jul 08, 2014 at 03:15:47PM -0700, Andy Lutomirski wrote: > In the event that anyone changes TASK_SIZE_MAX to equal the first > non-canonical address, then this is the least of your worries: someone > can put a syscall instruction at the very last canonical address, and > game over. You're right. > This bug affected a lot of operating systems a few years ago, but AFAIK > Linux was never vulnerable. Looks like it was until 18.104.22.168: http://lwn.net/Articles/137821/ Andi Kleen: [...] o x86_64: Add a guard page at the end of the 47bit address space o x86_64: Fix canonical checking for segment registers in ptrace o x86_64: check if ptrace RIP is canonical http://www.x86-64.org/pipermail/discuss/2005-May/006031.html https://kernel.googlesource.com/pub/scm/linux/kernel/git/stable/stable-queue/+/9cb395089b0a1aeaabd7900437c146a45a7ff067/22.214.171.124/x86_64-add-guard-page.patch "Add a guard page at the end of the 47bit address space. This works around a bug in the AMD K8 CPUs." https://access.redhat.com/security/cve/CVE-2005-1762 "The ptrace call in the Linux kernel 126.96.36.199 and 2.6.10 for the AMD64 platform allows local users to cause a denial of service (kernel crash) via a "non-canonical" address." So apparently the ptrace attack vector was tracked as CVE-2005-1762 at the time, whereas TASK_SIZE being equal to the first non-canonical address and triggering "a bug in the AMD K8 CPUs" (the known impact at the time, whatever it was) wasn't tracked as a security issue. Also related: "Bug 437712 - ptrace: PTRACE_SETREGS does not set RIP" https://bugzilla.redhat.com/show_bug.cgi?id=437712 (some discussion of an earlier fix at ptrace level, NOTABUG by that time). Alexander
Powered by blists - more mailing lists
Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.