On 08/14/16 at 12:25am, Brian Gerst wrote: > On Fri, Jul 8, 2016 at 4:35 PM, tip-bot for Thomas Garnier > <tipbot@xxxxxxxxx> wrote: > > Commit-ID: 021182e52fe01c1f7b126f97fd6ba048dc4234fd > > Gitweb: http://git.kernel.org/tip/021182e52fe01c1f7b126f97fd6ba048dc4234fd > > Author: Thomas Garnier <thgarnie@xxxxxxxxxx> > > AuthorDate: Tue, 21 Jun 2016 17:47:03 -0700 > > Committer: Ingo Molnar <mingo@xxxxxxxxxx> > > CommitDate: Fri, 8 Jul 2016 17:35:15 +0200 > > > > x86/mm: Enable KASLR for physical mapping memory regions > > > > Add the physical mapping in the list of randomized memory regions. > > > > The physical memory mapping holds most allocations from boot and heap > > allocators. Knowing the base address and physical memory size, an attacker > > can deduce the PDE virtual address for the vDSO memory page. This attack > > was demonstrated at CanSecWest 2016, in the following presentation: > > > > "Getting Physical: Extreme Abuse of Intel Based Paged Systems": > > https://github.com/n3k/CansecWest2016_Getting_Physical_Extreme_Abuse_of_Intel_Based_Paging_Systems/blob/master/Presentation/CanSec2016_Presentation.pdf > > > > (See second part of the presentation). > > > > The exploits used against Linux worked successfully against 4.6+ but > > fail with KASLR memory enabled: > > > > https://github.com/n3k/CansecWest2016_Getting_Physical_Extreme_Abuse_of_Intel_Based_Paging_Systems/tree/master/Demos/Linux/exploits > > > > Similar research was done at Google leading to this patch proposal. > > > > Variants exists to overwrite /proc or /sys objects ACLs leading to > > elevation of privileges. These variants were tested against 4.6+. > > > > The page offset used by the compressed kernel retains the static value > > since it is not yet randomized during this boot stage. > > This patch is causing my system to fail to boot. The last messages > that are printed before it hangs are: > > [ 0.195652] smpboot: CPU0: AMD Phenom(tm) II X6 1055T Processor > (family: 0x10, model: 0xa, stepping: 0x0) > [ 0.195656] Performance Events: AMD PMU driver. > [ 0.195659] ... version: 0 > [ 0.195660] ... bit width: 48 > [ 0.195660] ... generic registers: 4 > [ 0.195661] ... value mask: 0000ffffffffffff > [ 0.195662] ... max period: 00007fffffffffff > [ 0.195663] ... fixed-purpose events: 0 > [ 0.195664] ... event mask: 000000000000000f > [ 0.196185] NMI watchdog: enabled on all CPUs, permanently consumes > one hw-PMU counter. > [ 0.196291] x86: Booting SMP configuration: > [ 0.196292] .... node #0, CPUs: #1 > > I'm taking a guess here, but it may be that this is interfering with > the APIC accesses. Seems it hang when startup 2nd cpu. It may give more information if add below line to the beginning of arch/x86/kernel/smpboot.c and rebuild bzImage. #define DEBUG > > -- > Brian Gerst -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
|