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kernel: canaries: Add terminator character

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Add one character into stack canary.

Signed-off-by: Flavio Ceolin <flavio.ceolin@intel.com>
This commit is contained in:
Flavio Ceolin 2019-08-09 16:31:33 -07:00 • committed by Anas Nashif
commit 394f66b77e
1 changed files with 43 additions and 12 deletions
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55
kernel/init.c
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@ -426,35 +426,33 @@ static FUNC_NORETURN void switch_to_main_thread(void)
}
#endif /* CONFIG_MULTITHREADING */
u32_t z_early_boot_rand32_get(void)
static void z_early_boot_rand_get(u8_t *buf, size_t length)
{
int n = sizeof(u32_t);
#ifdef CONFIG_ENTROPY_HAS_DRIVER
struct device *entropy = device_get_binding(CONFIG_ENTROPY_NAME);
int rc;
u32_t retval;
if (entropy == NULL) {
goto sys_rand32_fallback;
goto sys_rand_fallback;
}
/* Try to see if driver provides an ISR-specific API */
rc = entropy_get_entropy_isr(entropy, (u8_t *)&retval,
sizeof(retval), ENTROPY_BUSYWAIT);
rc = entropy_get_entropy_isr(entropy, buf, length, ENTROPY_BUSYWAIT);
if (rc == -ENOTSUP) {
/* Driver does not provide an ISR-specific API, assume it can
* be called from ISR context
*/
rc = entropy_get_entropy(entropy, (u8_t *)&retval,
sizeof(retval));
rc = entropy_get_entropy(entropy, buf, length);
}
if (rc >= 0) {
return retval;
return;
}
/* Fall through to fallback */
sys_rand32_fallback:
sys_rand_fallback:
#endif
/* FIXME: this assumes sys_rand32_get() won't use any synchronization
@ -463,7 +461,34 @@ sys_rand32_fallback:
* devices are available should be built, this is only a fallback for
* those devices without a HWRNG entropy driver.
*/
return sys_rand32_get();
while (length > 0) {
u32_t rndbits;
u8_t *p_rndbits = (u8_t *)&rndbits;
rndbits = sys_rand32_get();
if (length < sizeof(u32_t)) {
n = length;
}
for (int i = 0; i < n; i++) {
*buf = *p_rndbits;
buf++;
p_rndbits++;
}
length -= n;
}
}
u32_t z_early_boot_rand32_get(void)
{
u32_t retval;
z_early_boot_rand_get((u8_t *)&retval, sizeof(retval));
return retval;
}
/**
@ -478,6 +503,10 @@ sys_rand32_fallback:
*/
FUNC_NORETURN void z_cstart(void)
{
#ifdef CONFIG_STACK_CANARIES
uintptr_t stack_guard;
#endif /* CONFIG_STACK_CANARIES */
/* gcov hook needed to get the coverage report.*/
gcov_static_init();
@ -506,8 +535,10 @@ FUNC_NORETURN void z_cstart(void)
z_sys_device_do_config_level(_SYS_INIT_LEVEL_PRE_KERNEL_2);
#ifdef CONFIG_STACK_CANARIES
__stack_chk_guard = z_early_boot_rand32_get();
#endif
z_early_boot_rand_get((u8_t *)&stack_guard, sizeof(stack_guard));
__stack_chk_guard = stack_guard;
__stack_chk_guard <<= 8;
#endif /* CONFIG_STACK_CANARIES */
#ifdef CONFIG_MULTITHREADING
prepare_multithreading(&dummy_thread);