diff options
Diffstat (limited to 'include/linux/stackprotector.h')
| -rw-r--r-- | include/linux/stackprotector.h | 22 |
1 files changed, 21 insertions, 1 deletions
diff --git a/include/linux/stackprotector.h b/include/linux/stackprotector.h index 6f3e54c704c0..9c88707d9a0f 100644 --- a/include/linux/stackprotector.h +++ b/include/linux/stackprotector.h @@ -1,3 +1,4 @@ +/* SPDX-License-Identifier: GPL-2.0 */ #ifndef _LINUX_STACKPROTECTOR_H #define _LINUX_STACKPROTECTOR_H 1 @@ -5,7 +6,26 @@ #include <linux/sched.h> #include <linux/random.h> -#ifdef CONFIG_CC_STACKPROTECTOR +/* + * On 64-bit architectures, protect against non-terminated C string overflows + * by zeroing out the first byte of the canary; this leaves 56 bits of entropy. + */ +#ifdef CONFIG_64BIT +# ifdef __LITTLE_ENDIAN +# define CANARY_MASK 0xffffffffffffff00UL +# else /* big endian, 64 bits: */ +# define CANARY_MASK 0x00ffffffffffffffUL +# endif +#else /* 32 bits: */ +# define CANARY_MASK 0xffffffffUL +#endif + +static inline unsigned long get_random_canary(void) +{ + return get_random_long() & CANARY_MASK; +} + +#if defined(CONFIG_STACKPROTECTOR) || defined(CONFIG_ARM64_PTR_AUTH) # include <asm/stackprotector.h> #else static inline void boot_init_stack_canary(void) |