KERN_INVALID_ADDRESS和KERN_PROTECTION_FAILURE之间有什么区别？ [英] What's the difference between KERN_INVALID_ADDRESS and KERN_PROTECTION_FAILURE?

问题描述

iPhone OS上 KERN_INVALID_ADDRESS 和 KERN_PROTECTION_FAILURE 之间的区别是什么？

What's the difference between KERN_INVALID_ADDRESS and KERN_PROTECTION_FAILURE on iPhone OS?

我有两个临时5分钟的特别测试版的崩溃报告，它们之间的主要区别（二进制图像：部分除外）就是这一部分：

I have two crash reports from an ad-hoc beta tester that are 5 minutes apart and the main difference between them (other than the "Binary Images:" section) is this section:

报告A：

Exception Type:  EXC_BAD_ACCESS (SIGBUS)
Exception Codes: KERN_PROTECTION_FAILURE at 0x00000008

报告B：

Exception Type:  EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: KERN_INVALID_ADDRESS at 0x67696c69

对于它的价值，两者都有这样的痕迹：

For what it's worth, both have this trace:

Thread 0 Crashed:
0   libobjc.A.dylib                 0x30011940 objc_msgSend + 20
1   UIKit                           0x30940174 -[UIWindow _shouldAutorotateToInterfaceOrientation:] + 60
2   UIKit                           0x30a223d8 -[UIWindow _updateToInterfaceOrientation:duration:force:] + 36
3   UIKit                           0x30958638 -[UIWindow _updateInterfaceOrientationFromDeviceOrientation] + 112
4   UIKit                           0x30942514 -[UIWindow _handleDeviceOrientationChange:] + 72
5   Foundation                      0x3054dc7a _nsnote_callback + 178
6   CoreFoundation                  0x3024ea52 _CFXNotificationPostNotification + 298
7   Foundation                      0x3054b854 -[NSNotificationCenter postNotificationName:object:userInfo:] + 64
8   UIKit                           0x309414a4 -[UIDevice setOrientation:] + 124
9   UIKit                           0x30938330 -[UIApplication handleEvent:withNewEvent:] + 5232
10  UIKit                           0x30936ce8 -[UIApplication sendEvent:] + 60
11  UIKit                           0x30936874 _UIApplicationHandleEvent + 4336
12  GraphicsServices                0x32046964 PurpleEventCallback + 1028
13  CoreFoundation                  0x30254a70 CFRunLoopRunSpecific + 2296
14  CoreFoundation                  0x30254164 CFRunLoopRunInMode + 44
15  GraphicsServices                0x3204529c GSEventRunModal + 188
16  UIKit                           0x308f0374 -[UIApplication _run] + 552
17  UIKit                           0x308eea8c UIApplicationMain + 960
18  MyApp                           0x00015e24 0x1000 + 85540
19  MyApp                           0x0000f138 0x1000 + 57656

另外，我没有在我的代码中的任何地方实现shouldAutorotateToInterfaceOrientation：方法。

Also, I do not implement the "shouldAutorotateToInterfaceOrientation:" method anywhere in my code.

推荐答案

EXC_BAD_ACCESS（SIGBUS）KERN_PROTECTION_FAILURE 表示虚拟地址明显错误：大多数CPU必须访问某个字节边界的内存。因为此处的数据访问是针对64位值（8）对齐的，所以它必须尝试执行获取128位值的指令（例如比较和交换指令 CMPXCHG16B ）。在任何情况下，您可以从这里的示例中看到它是 0x00000008 ，这可能意味着您正在访问一个从开头偏移8个字节的结构元素，但是您的结构指针是 NULL 。

EXC_BAD_ACCESS (SIGBUS) KERN_PROTECTION_FAILURE means that the virtual address is obviously wrong: most CPUs must access memory on a certain byte boundary. Because your data access here is aligned for a 64-bit value (8), it must be trying to execute an instruction that fetches a 128-bit value (such as compare and exchange instruction CMPXCHG16B). In any case, you can see from the example here that it's 0x00000008, which probably means you're accessing a structure element that's offset 8 bytes from the beginning, but your structure pointer is NULL.

EXC_BAD_ACCESS（SIGSEGV）KERN_INVALID_ADDRESS 表示您正在参考的虚拟地址不在页面表中，或者您没有访问权限。这是一个您不允许访问的虚拟地址。对于您的示例地址 0x67696c69 ，这可能不是指针被视为指针;或者包含指针的数据结构是免费的并被其他数据覆盖。

EXC_BAD_ACCESS (SIGSEGV) KERN_INVALID_ADDRESS means that the virtual address you're refererencing is not in the page tables or you don't have access. It's a virtual address that you're not allowed to access. For your example address address 0x67696c69 it's likely that this is something that is not a pointer that was treated like a pointer; or your data structure that contains the pointer was free'd and overwritten with other data.

对于 KERN_INVALID_ADDRESS 示例，指针数据拼出ASCII'ilig'（因为它是小端）。因此，存储指针的内存可能会被某种字符串覆盖。

For your KERN_INVALID_ADDRESS example, the pointer data spells out ASCII 'ilig' (because it's little endian). Therefore the memory where your pointer was stored was likely overwritten with some sort of string.

在这两种情况下，都可能会覆盖<$ c $中的数据结构。 c> UIWindow 。

In both cases, it's likely that something overwrote the data structures in your UIWindow.

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