Date: Thu, 19 Jun 2014 23:37:39 -0400 From: Steve Grubb <sgrubb@...hat.com> To: oss-security@...ts.openwall.com Cc: Andy Lutomirski <luto@...capital.net>, Linux Audit <linux-audit@...hat.com> Subject: Re: CVE request: Another Linux syscall auditing bug Hi, Reminder again...please report bugs to linux-audit mail list. On Thursday, June 19, 2014 06:26:38 PM Andy Lutomirski wrote: > On a 32-bit x86 kernel with syscall auditing enabled, syscall(1000) > will cause an OOPS. This problem goes at least as far back as Linux > 3.11 and appears to be present in Linux 3.15 as well. I suspect that > this bug is very old. > > In order to see this bug, you'll need syscall auditing on (auditctl -e > 1 will do that) and you'll need 'sep' in flags in /proc/cpuinfo. That > means that qemu -cpu qemu64 will not be exposed to this bug, but qemu > -cpu host will on any recent CPU. > > Mitigations include: > - Running under ptrace or strace. > - Using any seccomp filter at all (phew!) > - Turning off SEP (which is a big slowdown on all syscalls) > - auditctl -a task,never > > I'd be rather surprised if this can be used for anything other than > DoS, although the same underlying bug could potentially have more > serious consequences. > > This bug was found (inadvertently, I presume) by Toralf Förster. The > patch here: > > http://lkml.kernel.org/g/CALCETrW7U4AHG-a9oPbOt31z3wgzhjSu8b+yGpdM4+vNinKgsA > @mail.gmail.com > > is reported to fix the bug, but it should not be considered to be > well-tested. > > --Andy
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