Blame SOURCES/cve-2017-13695.patch

9897bb
From 37f2c716f2c6ab14c3ba557a539c3ee3224931b5 Mon Sep 17 00:00:00 2001
9897bb
From: Seunghun Han <kkamagui@gmail.com>
9897bb
Date: Wed, 19 Jul 2017 17:04:44 +0900
9897bb
Subject: [PATCH] acpi: acpica: fix acpi operand cache leak in nseval.c
9897bb
9897bb
I found an ACPI cache leak in ACPI early termination and boot continuing case.
9897bb
9897bb
When early termination occurs due to malicious ACPI table, Linux kernel
9897bb
terminates ACPI function and continues to boot process. While kernel terminates
9897bb
ACPI function, kmem_cache_destroy() reports Acpi-Operand cache leak.
9897bb
9897bb
Boot log of ACPI operand cache leak is as follows:
9897bb
>[    0.464168] ACPI: Added _OSI(Module Device)
9897bb
>[    0.467022] ACPI: Added _OSI(Processor Device)
9897bb
>[    0.469376] ACPI: Added _OSI(3.0 _SCP Extensions)
9897bb
>[    0.471647] ACPI: Added _OSI(Processor Aggregator Device)
9897bb
>[    0.477997] ACPI Error: Null stack entry at ffff880215c0aad8 (20170303/exresop-174)
9897bb
>[    0.482706] ACPI Exception: AE_AML_INTERNAL, While resolving operands for [OpcodeName unavailable] (20170303/dswexec-461)
9897bb
>[    0.487503] ACPI Error: Method parse/execution failed [\DBG] (Node ffff88021710ab40), AE_AML_INTERNAL (20170303/psparse-543)
9897bb
>[    0.492136] ACPI Error: Method parse/execution failed [\_SB._INI] (Node ffff88021710a618), AE_AML_INTERNAL (20170303/psparse-543)
9897bb
>[    0.497683] ACPI: Interpreter enabled
9897bb
>[    0.499385] ACPI: (supports S0)
9897bb
>[    0.501151] ACPI: Using IOAPIC for interrupt routing
9897bb
>[    0.503342] ACPI Error: Null stack entry at ffff880215c0aad8 (20170303/exresop-174)
9897bb
>[    0.506522] ACPI Exception: AE_AML_INTERNAL, While resolving operands for [OpcodeName unavailable] (20170303/dswexec-461)
9897bb
>[    0.510463] ACPI Error: Method parse/execution failed [\DBG] (Node ffff88021710ab40), AE_AML_INTERNAL (20170303/psparse-543)
9897bb
>[    0.514477] ACPI Error: Method parse/execution failed [\_PIC] (Node ffff88021710ab18), AE_AML_INTERNAL (20170303/psparse-543)
9897bb
>[    0.518867] ACPI Exception: AE_AML_INTERNAL, Evaluating _PIC (20170303/bus-991)
9897bb
>[    0.522384] kmem_cache_destroy Acpi-Operand: Slab cache still has objects
9897bb
>[    0.524597] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.12.0-rc5 #26
9897bb
>[    0.526795] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
9897bb
>[    0.529668] Call Trace:
9897bb
>[    0.530811]  ? dump_stack+0x5c/0x81
9897bb
>[    0.532240]  ? kmem_cache_destroy+0x1aa/0x1c0
9897bb
>[    0.533905]  ? acpi_os_delete_cache+0xa/0x10
9897bb
>[    0.535497]  ? acpi_ut_delete_caches+0x3f/0x7b
9897bb
>[    0.537237]  ? acpi_terminate+0xa/0x14
9897bb
>[    0.538701]  ? acpi_init+0x2af/0x34f
9897bb
>[    0.540008]  ? acpi_sleep_proc_init+0x27/0x27
9897bb
>[    0.541593]  ? do_one_initcall+0x4e/0x1a0
9897bb
>[    0.543008]  ? kernel_init_freeable+0x19e/0x21f
9897bb
>[    0.546202]  ? rest_init+0x80/0x80
9897bb
>[    0.547513]  ? kernel_init+0xa/0x100
9897bb
>[    0.548817]  ? ret_from_fork+0x25/0x30
9897bb
>[    0.550587] vgaarb: loaded
9897bb
>[    0.551716] EDAC MC: Ver: 3.0.0
9897bb
>[    0.553744] PCI: Probing PCI hardware
9897bb
>[    0.555038] PCI host bridge to bus 0000:00
9897bb
> ... Continue to boot and log is omitted ...
9897bb
9897bb
I analyzed this memory leak in detail and found AcpiNsEvaluate() function
9897bb
only removes Info->ReturnObject in AE_CTRL_RETURN_VALUE case. But, when errors
9897bb
occur, the status value is not AE_CTRL_RETURN_VALUE, and Info->ReturnObject is
9897bb
also not null. Therefore, this causes acpi operand memory leak.
9897bb
9897bb
This cache leak causes a security threat because an old kernel (<= 4.9) shows
9897bb
memory locations of kernel functions in stack dump. Some malicious users
9897bb
could use this information to neutralize kernel ASLR.
9897bb
9897bb
I made a patch to fix ACPI operand cache leak.
9897bb
9897bb
Signed-off-by: Seunghun Han <kkamagui@gmail.com>
9897bb
9897bb
Github-Location: https://github.com/acpica/acpica/pull/296/commits/37f2c716f2c6ab14c3ba557a539c3ee3224931b5
9897bb
9897bb
---
9897bb
 source/components/namespace/nseval.c | 10 ++++++++++
9897bb
 1 file changed, 10 insertions(+)
9897bb
9897bb
Index: acpica-unix2-20200925/source/components/namespace/nseval.c
9897bb
===================================================================
9897bb
--- acpica-unix2-20200925.orig/source/components/namespace/nseval.c
9897bb
+++ acpica-unix2-20200925/source/components/namespace/nseval.c
9897bb
@@ -329,6 +329,16 @@ AcpiNsEvaluate (
9897bb
             Info->ReturnObject = NULL;
9897bb
         }
9897bb
     }
9897bb
+    else if (ACPI_FAILURE(Status)) 
9897bb
+    {
9897bb
+        /* If ReturnObject exists, delete it */
9897bb
+
9897bb
+        if (Info->ReturnObject) 
9897bb
+        {
9897bb
+            AcpiUtRemoveReference (Info->ReturnObject);
9897bb
+            Info->ReturnObject = NULL;
9897bb
+        }
9897bb
+    }
9897bb
 
9897bb
     ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
9897bb
         "*** Completed evaluation of object %s ***\n",