boot_init_stack_canary

[Author: Bo Shen <[e-mail]>]

[Linux kernel: git: 0c0bd34]

<arch/arm/include/asm/stackprotector.h>

  1 /*                                                                           2  * GCC stack protector support.   3  *                               4  * Stack protector works by putting predefined pattern at the start of   5  * the stack frame and verifying that it hasn't been overwritten when   6  * returning from the function.  The pattern is called stack canary          7  * and gcc expects it to be defined by a global variable called              8  * "__stack_chk_guard" on ARM.  This unfortunately means that on SMP         9  * we cannot have a different canary value per task.                        10  */                                                                         11                                                                             12 #ifndef _ASM_STACKPROTECTOR_H                                               13 #define _ASM_STACKPROTECTOR_H 1                                             14                                                                             15 #include <linux/random.h>                                                   16 #include <linux/version.h>                                                  17                                                                             18 extern unsigned long __stack_chk_guard;                                     19                                                                             20 /*                                                                          21  * Initialize the stackprotector canary value.                              22  *                                                                          23  * NOTE: this must only be called from functions that never return,         24  * and it must always be inlined.                                           25  */                                                                         26 static __always_inline void boot_init_stack_canary(void)                    27 {                                                                           28         unsigned long canary;                                               29                                                                             30         /* Try to get a semi random initial value. */                       31         get_random_bytes(&canary, sizeof(canary));                          32         canary ^= LINUX_VERSION_CODE;                                       33                                                                             34         current->stack_canary = canary;                                     35         __stack_chk_guard = current->stack_canary;                          36 }                                                                           37                                                                             38 #endif  /* _ASM_STACKPROTECTOR_H */          

这代码具体做何用处还不知道，暂时不表。