lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Sun, 19 Feb 2012 12:45:09 -0800 From: "H. Peter Anvin" <hpa@...or.com> To: Steven Rostedt <rostedt@...dmis.org> CC: Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org, Andrew Morton <akpm@...ux-foundation.org>, Peter Zijlstra <a.p.zijlstra@...llo.nl> Subject: Re: [PATCH][GIT PULL][v3.3] x86: Test saved %rip in NMI to determine nested NMI On 02/19/2012 12:34 PM, Steven Rostedt wrote: > On Sun, 2012-02-19 at 05:46 -0800, hpanvin@...il.com wrote: >> Vsyscall page, not vdso... > > Peter, > > My original patch was to check the %cs register against __KERNEL_CS, but > IIRC, you said that userspace can change that register to anything it > wanted before doing a long jump or something. Is this true for x86_64 as > well? I guess it would be because x86_64 can support 32bit apps. > > Anyway, I'll add a check that makes sure that the RIP is less than the > FIXADDR sections as well. > User space can change %cs, but it can never set it to __KERNEL_CS; specifically user space can never set the bottom two bits in CS to zero. So this should be a better test. (Now, doing the test that way plays havoc with the braindamage knows as Xen paravirt, but I don't think it's subject to this particular NMI code.) -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists