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Commit | Line | Data |
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c743f380 NP |
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 */ |