CVE-2017-15595 : Detail

CVE-2017-15595

8.8
/
High
0.1%V3
Local
2017-10-18
06h00 +00:00
2018-10-30
08h57 +00:00
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CVE Descriptions

An issue was discovered in Xen through 4.9.x allowing x86 PV guest OS users to cause a denial of service (unbounded recursion, stack consumption, and hypervisor crash) or possibly gain privileges via crafted page-table stacking.

CVE Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE-400 Uncontrolled Resource Consumption
The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources.

Metrics

Metrics Score Severity CVSS Vector Source
V3.0 8.8 HIGH CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Base: Exploitabilty Metrics

The Exploitability metrics reflect the characteristics of the thing that is vulnerable, which we refer to formally as the vulnerable component.

Attack Vector

This metric reflects the context by which vulnerability exploitation is possible.

Local

A vulnerability exploitable with Local access means that the vulnerable component is not bound to the network stack, and the attacker's path is via read/write/execute capabilities. In some cases, the attacker may be logged in locally in order to exploit the vulnerability, otherwise, she may rely on User Interaction to execute a malicious file.

Attack Complexity

This metric describes the conditions beyond the attacker's control that must exist in order to exploit the vulnerability.

Low

Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.

Privileges Required

This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability.

Low

The attacker is authorized with (i.e. requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.

User Interaction

This metric captures the requirement for a user, other than the attacker, to participate in the successful compromise of the vulnerable component.

None

The vulnerable system can be exploited without interaction from any user.

Base: Scope Metrics

An important property captured by CVSS v3.0 is the ability for a vulnerability in one software component to impact resources beyond its means, or privileges.

Scope

Formally, Scope refers to the collection of privileges defined by a computing authority (e.g. an application, an operating system, or a sandbox environment) when granting access to computing resources (e.g. files, CPU, memory, etc). These privileges are assigned based on some method of identification and authorization. In some cases, the authorization may be simple or loosely controlled based upon predefined rules or standards. For example, in the case of Ethernet traffic sent to a network switch, the switch accepts traffic that arrives on its ports and is an authority that controls the traffic flow to other switch ports.

Changed

An exploited vulnerability can affect resources beyond the authorization privileges intended by the vulnerable component. In this case the vulnerable component and the impacted component are different.

Base: Impact Metrics

The Impact metrics refer to the properties of the impacted component.

Confidentiality Impact

This metric measures the impact to the confidentiality of the information resources managed by a software component due to a successfully exploited vulnerability.

High

There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.

Integrity Impact

This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information.

High

There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.

Availability Impact

This metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability.

High

There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Temporal Metrics

The Temporal metrics measure the current state of exploit techniques or code availability, the existence of any patches or workarounds, or the confidence that one has in the description of a vulnerability.

Environmental Metrics

 [email protected]
V2 7.2 AV:L/AC:L/Au:N/C:C/I:C/A:C [email protected]

EPSS

EPSS is a scoring model that predicts the likelihood of a vulnerability being exploited.

EPSS Score

The EPSS model produces a probability score between 0 and 1 (0 and 100%). The higher the score, the greater the probability that a vulnerability will be exploited.

EPSS Percentile

The percentile is used to rank CVE according to their EPSS score. For example, a CVE in the 95th percentile according to its EPSS score is more likely to be exploited than 95% of other CVE. Thus, the percentile is used to compare the EPSS score of a CVE with that of other CVE.
EPSS First.org

Exploit information

Exploit Database EDB-ID : 43014

Publication date : 2017-10-17
22h00 +00:00
Author : Google Security Research
EDB Verified : Yes

Xen allows pagetables of the same level to map each other as readonly in PV domains. This is useful if a guest wants to use the self-referential pagetable trick for easy access to pagetables by mapped virtual address. When cleaning up a pagetable after the last typed reference to it has been dropped (via __put_page_type() -> __put_final_page_type() -> free_page_type()), Xen will recursively drop the typed refcounts of pages referenced by the pagetable, potentially recursively cleaning them up as well. For normal pagetables, the recursion depth is bounded by the number of paging levels the architecture supports. However, no such depth limit exists for pagetables of the same depth that map each other. The attached PoC will set up a chain of 1000 L4 pagetables such that the first pagetable is type-pinned and each following pagetable is referenced by the previous one. Then, the type-pin of the first pagetable is removed, and the following 999 pagetables are recursively cleaned up, causing a stack overflow. To run the PoC in a PV domain, install kernel headers, then run ./compile, then load the built module via insmod. Xen console output caused by running the PoC inside a normal PV domain: ============================== (XEN) Xen version 4.8.1 (Debian 4.8.1-1+deb9u3) ([email protected]) (gcc (Debian 6.3.0-18) 6.3.0 20170516) debug=n Thu Sep 7 18:24:26 UTC 2017 (XEN) Bootloader: GRUB 2.02~beta3-5 (XEN) Command line: loglvl=all com1=115200,8n1,pci console=com1 placeholder (XEN) Video information: (XEN) VGA is text mode 80x25, font 8x16 (XEN) Disc information: (XEN) Found 1 MBR signatures (XEN) Found 1 EDD information structures (XEN) Xen-e820 RAM map: (XEN) 0000000000000000 - 000000000009fc00 (usable) (XEN) 000000000009fc00 - 00000000000a0000 (reserved) (XEN) 00000000000f0000 - 0000000000100000 (reserved) (XEN) 0000000000100000 - 00000000dfff0000 (usable) (XEN) 00000000dfff0000 - 00000000e0000000 (ACPI data) (XEN) 00000000fec00000 - 00000000fec01000 (reserved) (XEN) 00000000fee00000 - 00000000fee01000 (reserved) (XEN) 00000000fffc0000 - 0000000100000000 (reserved) (XEN) 0000000100000000 - 0000000120000000 (usable) (XEN) ACPI: RSDP 000E0000, 0024 (r2 VBOX ) (XEN) ACPI: XSDT DFFF0030, 003C (r1 VBOX VBOXXSDT 1 ASL 61) (XEN) ACPI: FACP DFFF00F0, 00F4 (r4 VBOX VBOXFACP 1 ASL 61) (XEN) ACPI: DSDT DFFF0470, 210F (r1 VBOX VBOXBIOS 2 INTL 20140214) (XEN) ACPI: FACS DFFF0200, 0040 (XEN) ACPI: APIC DFFF0240, 0054 (r2 VBOX VBOXAPIC 1 ASL 61) (XEN) ACPI: SSDT DFFF02A0, 01CC (r1 VBOX VBOXCPUT 2 INTL 20140214) (XEN) System RAM: 4095MB (4193852kB) (XEN) No NUMA configuration found (XEN) Faking a node at 0000000000000000-0000000120000000 (XEN) Domain heap initialised (XEN) CPU Vendor: Intel, Family 6 (0x6), Model 78 (0x4e), Stepping 3 (raw 000406e3) (XEN) found SMP MP-table at 0009fff0 (XEN) DMI 2.5 present. (XEN) Using APIC driver default (XEN) ACPI: PM-Timer IO Port: 0x4008 (32 bits) (XEN) ACPI: SLEEP INFO: pm1x_cnt[1:4004,1:0], pm1x_evt[1:4000,1:0] (XEN) ACPI: wakeup_vec[dfff020c], vec_size[20] (XEN) ACPI: Local APIC address 0xfee00000 (XEN) ACPI: LAPIC (acpi_id[0x00] lapic_id[0x00] enabled) (XEN) ACPI: IOAPIC (id[0x01] address[0xfec00000] gsi_base[0]) (XEN) IOAPIC[0]: apic_id 1, version 32, address 0xfec00000, GSI 0-23 (XEN) ACPI: INT_SRC_OVR (bus 0 bus_irq 0 global_irq 2 dfl dfl) (XEN) ACPI: INT_SRC_OVR (bus 0 bus_irq 9 global_irq 9 high level) (XEN) ACPI: IRQ0 used by override. (XEN) ACPI: IRQ2 used by override. (XEN) ACPI: IRQ9 used by override. (XEN) Enabling APIC mode: Flat. Using 1 I/O APICs (XEN) ERST table was not found (XEN) Using ACPI (MADT) for SMP configuration information (XEN) SMP: Allowing 1 CPUs (0 hotplug CPUs) (XEN) IRQ limits: 24 GSI, 184 MSI/MSI-X (XEN) Not enabling x2APIC: depends on iommu_supports_eim. (XEN) xstate: size: 0x440 and states: 0x7 (XEN) CPU0: No MCE banks present. Machine check support disabled (XEN) Using scheduler: SMP Credit Scheduler (credit) (XEN) Platform timer is 3.579MHz ACPI PM Timer (XEN) Detected 2807.850 MHz processor. (XEN) Initing memory sharing. (XEN) alt table ffff82d0802bcf38 -> ffff82d0802be594 (XEN) I/O virtualisation disabled (XEN) nr_sockets: 1 (XEN) ENABLING IO-APIC IRQs (XEN) -> Using new ACK method (XEN) ..TIMER: vector=0xF0 apic1=0 pin1=2 apic2=-1 pin2=-1 (XEN) Allocated console ring of 16 KiB. (XEN) Brought up 1 CPUs (XEN) build-id: cd504b2b380e2fe1265376aa845a404b9eb86982 (XEN) CPUIDLE: disabled due to no HPET. Force enable with 'cpuidle'. (XEN) ACPI sleep modes: S3 (XEN) VPMU: disabled (XEN) xenoprof: Initialization failed. Intel processor family 6 model 78is not supported (XEN) Dom0 has maximum 208 PIRQs (XEN) NX (Execute Disable) protection active (XEN) *** LOADING DOMAIN 0 *** (XEN) Xen kernel: 64-bit, lsb, compat32 (XEN) Dom0 kernel: 64-bit, PAE, lsb, paddr 0x1000000 -> 0x1f5a000 (XEN) PHYSICAL MEMORY ARRANGEMENT: (XEN) Dom0 alloc.: 0000000118000000->000000011a000000 (989666 pages to be allocated) (XEN) Init. ramdisk: 000000011ed74000->000000011ffff3b5 (XEN) VIRTUAL MEMORY ARRANGEMENT: (XEN) Loaded kernel: ffffffff81000000->ffffffff81f5a000 (XEN) Init. ramdisk: 0000000000000000->0000000000000000 (XEN) Phys-Mach map: 0000008000000000->00000080007a6370 (XEN) Start info: ffffffff81f5a000->ffffffff81f5a4b4 (XEN) Page tables: ffffffff81f5b000->ffffffff81f6e000 (XEN) Boot stack: ffffffff81f6e000->ffffffff81f6f000 (XEN) TOTAL: ffffffff80000000->ffffffff82000000 (XEN) ENTRY ADDRESS: ffffffff81d38180 (XEN) Dom0 has maximum 1 VCPUs (XEN) Scrubbing Free RAM on 1 nodes using 1 CPUs (XEN) ....................................done. (XEN) Initial low memory virq threshold set at 0x4000 pages. (XEN) Std. Loglevel: All (XEN) Guest Loglevel: Nothing (Rate-limited: Errors and warnings) (XEN) *** Serial input -> DOM0 (type 'CTRL-a' three times to switch input to Xen) (XEN) Freed 312kB init memory mapping kernel into physical memory about to get started... (XEN) d0 attempted to change d0v0's CR4 flags 00000620 -> 00040660 (XEN) PCI add device 0000:00:00.0 (XEN) PCI add device 0000:00:01.0 (XEN) PCI add device 0000:00:01.1 (XEN) PCI add device 0000:00:02.0 (XEN) PCI add device 0000:00:03.0 (XEN) PCI add device 0000:00:04.0 (XEN) PCI add device 0000:00:05.0 (XEN) PCI add device 0000:00:06.0 (XEN) PCI add device 0000:00:07.0 (XEN) PCI add device 0000:00:08.0 (XEN) PCI add device 0000:00:0d.0 Debian GNU/Linux 9 xenhost hvc0 xenhost login: (XEN) d1 attempted to change d1v0's CR4 flags 00000620 -> 00040660 (XEN) d1 attempted to change d1v1's CR4 flags 00000620 -> 00040660 (XEN) *** DOUBLE FAULT *** (XEN) ----[ Xen-4.8.1 x86_64 debug=n Not tainted ]---- (XEN) CPU: 0 (XEN) RIP: e008:[<ffff82d08017962a>] free_page_type+0xea/0x630 (XEN) RFLAGS: 0000000000010206 CONTEXT: hypervisor (XEN) rax: 000000000000a3db rbx: ffff82e000147b60 rcx: 0000000000000000 (XEN) rdx: ffff830000000000 rsi: 4000000000000000 rdi: 000000000000a3db (XEN) rbp: 4400000000000001 rsp: ffff8300dfce5ff8 r8: ffff8300dfce7fff (XEN) r9: ffff82d0802f2980 r10: 0000000000000000 r11: 0000000000000202 (XEN) r12: 000000000000a3db r13: ffff83011fd74000 r14: ffff83011fd74000 (XEN) r15: 0000000000000000 cr0: 000000008005003b cr4: 00000000000406a0 (XEN) cr3: 000000000702d000 cr2: ffff8300dfce5fe8 (XEN) ds: 0000 es: 0000 fs: 0000 gs: 0000 ss: e010 cs: e008 (XEN) Valid stack range: ffff8300dfce6000-ffff8300dfce8000, sp=ffff8300dfce5ff8, tss.esp0=ffff8300dfce7fc0 (XEN) Xen stack overflow (dumping trace ffff8300dfce6000-ffff8300dfce8000): (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d08016af21>] io_apic.c#ack_edge_ioapic_irq+0x11/0x60 (XEN) [<ffff82d08016af21>] io_apic.c#ack_edge_ioapic_irq+0x11/0x60 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d0801793ae>] mm.c#get_page_from_pagenr+0x4e/0x60 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d0801768e9>] is_iomem_page+0x9/0x70 (XEN) [<ffff82d08010baec>] grant_table.c#__gnttab_unmap_common_complete+0x17c/0x360 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080146684>] serial_tx_interrupt+0xe4/0x120 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017234a>] do_IRQ+0x22a/0x660 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080237f6f>] common_interrupt+0x5f/0x70 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d08017a028>] put_page_from_l1e+0xb8/0x130 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d08017a28a>] mm.c#put_page_from_l2e+0x7a/0x190 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d08017a438>] mm.c#put_page_from_l4e+0x88/0xc0 (XEN) [<ffff82d080179697>] free_page_type+0x157/0x630 (XEN) [<ffff82d0801793ae>] mm.c#get_page_from_pagenr+0x4e/0x60 (XEN) [<ffff82d080179cdf>] mm.c#__put_page_type+0x16f/0x290 (XEN) [<ffff82d0801791e3>] get_page+0x13/0xf0 (XEN) [<ffff82d080183056>] do_mmuext_op+0x1056/0x1500 (XEN) [<ffff82d080182000>] do_mmuext_op+0/0x1500 (XEN) [<ffff82d080169c96>] pv_hypercall+0xf6/0x1c0 (XEN) [<ffff82d08019bea3>] do_page_fault+0x163/0x4c0 (XEN) [<ffff82d080237abe>] entry.o#test_all_events+0/0x2a (XEN) (XEN) (XEN) **************************************** (XEN) Panic on CPU 0: (XEN) DOUBLE FAULT -- system shutdown (XEN) **************************************** (XEN) (XEN) Reboot in five seconds... ============================== This PoC just causes a DoS, but as far as I can tell, Xen only uses guard pages for the stack (via memguard_guard_stack()) in debug builds, which would mean that this is a potentially exploitable issue in release builds. Proof of Concept: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/43014.zip

Products Mentioned

Configuraton 0

Xen>>Xen >> Version To (including) 4.9.0

References

https://www.debian.org/security/2017/dsa-4050
Tags : vendor-advisory, x_refsource_DEBIAN
https://www.exploit-db.com/exploits/43014/
Tags : exploit, x_refsource_EXPLOIT-DB
https://security.gentoo.org/glsa/201801-14
Tags : vendor-advisory, x_refsource_GENTOO