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Differential D15173 Diff 41808 head/lib/libc/secure/stack_protector.c

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head/lib/libc/secure/stack_protector.c

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void __stack_chk_fail(void); void __stack_chk_fail(void);
void __chk_fail(void); void __chk_fail(void);
/*LINTED used*/ /*LINTED used*/
static void static void
__guard_setup(void) __guard_setup(void)
{ {
static const int mib[2] = { CTL_KERN, KERN_ARND }; static const int mib[2] = { CTL_KERN, KERN_ARND };
volatile long tmp_stack_chk_guard[nitems(__stack_chk_guard)];
size_t len; size_t len;
int error; int error, idx;
if (__stack_chk_guard[0] != 0) if (__stack_chk_guard[0] != 0)
return; return;
error = _elf_aux_info(AT_CANARY, __stack_chk_guard, /*
sizeof(__stack_chk_guard)); * Avoid using functions which might have stack protection
if (error == 0 && __stack_chk_guard[0] != 0) * enabled, to update the __stack_chk_guard. First fetch the
* data into a temporal array, then do manual volatile copy to
* not allow optimizer to call memcpy() behind us.
*/
error = _elf_aux_info(AT_CANARY, (void *)tmp_stack_chk_guard,
sizeof(tmp_stack_chk_guard));
if (error == 0 && tmp_stack_chk_guard[0] != 0) {
for (idx = 0; idx < nitems(__stack_chk_guard); idx++) {
__stack_chk_guard[idx] = tmp_stack_chk_guard[idx];
tmp_stack_chk_guard[idx] = 0;
}
return; return;
}
len = sizeof(__stack_chk_guard); len = sizeof(__stack_chk_guard);
if (__sysctl(mib, nitems(mib), __stack_chk_guard, &len, NULL, 0) == if (__sysctl(mib, nitems(mib), __stack_chk_guard, &len, NULL, 0) ==
-1 || len != sizeof(__stack_chk_guard)) { -1 || len != sizeof(__stack_chk_guard)) {
/* If sysctl was unsuccessful, use the "terminator canary". */ /* If sysctl was unsuccessful, use the "terminator canary". */
((unsigned char *)(void *)__stack_chk_guard)[0] = 0; ((unsigned char *)(void *)__stack_chk_guard)[0] = 0;
((unsigned char *)(void *)__stack_chk_guard)[1] = 0; ((unsigned char *)(void *)__stack_chk_guard)[1] = 0;
((unsigned char *)(void *)__stack_chk_guard)[2] = '\n'; ((unsigned char *)(void *)__stack_chk_guard)[2] = '\n';
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