Linux 段错误类型

There are three kinds of SEGV, which is an error that results from an invalid memory access:

1. A page was accessed which had the wrong permissions. E.g., it was read-only but your code tried to write to it. This will be reported as SEGV_ACCERR.
2. A page was accessed that is not even mapped into the address space of the application at all. This will often result from dereferencing a null pointer or a pointer that was corrupted with a small integer value. This is reported as SEGV_MAPERR.
3. A new SEGV error code SEGV_BNDERR is introduced in new kernel.

可以参考 Linux kernel 源代码中的 include/uapi/asm-generic/siginfo.h 文件：

/*
 * SIGSEGV si_codes
 */
#define SEGV_MAPERR     (__SI_FAULT|1)  /* address not mapped to object */
#define SEGV_ACCERR     (__SI_FAULT|2)  /* invalid permissions for mapped object */
#define SEGV_BNDERR     (__SI_FAULT|3)  /* failed address bound checks */
#define NSIGSEGV        3