asan.c

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/* SPDX-License-Identifier: GPL-2.0-only */
 
/*
 * Address sanitizer support.
 *
 * Parts of this file are based on mm/kasan
 * from the Linux kernel 4.19.137.
 *
 */
 
#include <console/console.h>
#include <symbols.h>
#include <assert.h>
#include <arch/symbols.h>
#include <asan.h>
 
static inline void *asan_mem_to_shadow(const void *addr)
{
#if ENV_ROMSTAGE
        return (void *)((uintptr_t)&_asan_shadow + (((uintptr_t)addr -
                (uintptr_t)&_car_region_start) >> ASAN_SHADOW_SCALE_SHIFT));
#elif ENV_RAMSTAGE
        return (void *)((uintptr_t)&_asan_shadow + (((uintptr_t)addr -
                (uintptr_t)&_data) >> ASAN_SHADOW_SCALE_SHIFT));
#endif
}
 
static inline const void *asan_shadow_to_mem(const void *shadow_addr)
{
#if ENV_ROMSTAGE
        return (void *)((uintptr_t)&_car_region_start + (((uintptr_t)shadow_addr -
                (uintptr_t)&_asan_shadow) << ASAN_SHADOW_SCALE_SHIFT));
#elif ENV_RAMSTAGE
        return (void *)((uintptr_t)&_data + (((uintptr_t)shadow_addr -
                (uintptr_t)&_asan_shadow) << ASAN_SHADOW_SCALE_SHIFT));
#endif
}
 
static void asan_poison_shadow(const void *address, size_t size, u8 value)
{
        void *shadow_start, *shadow_end;
 
        shadow_start = asan_mem_to_shadow(address);
        shadow_end = asan_mem_to_shadow(address + size);
 
        __builtin_memset(shadow_start, value, shadow_end - shadow_start);
}
 
void asan_unpoison_shadow(const void *address, size_t size)
{
        asan_poison_shadow(address, size, 0);
 
        if (size & ASAN_SHADOW_MASK) {
                u8 *shadow = (u8 *)asan_mem_to_shadow(address + size);
                *shadow = size & ASAN_SHADOW_MASK;
        }
}
 
static __always_inline bool memory_is_poisoned_1(unsigned long addr)
{
        s8 shadow_value = *(s8 *)asan_mem_to_shadow((void *)addr);
 
        if (unlikely(shadow_value)) {
                s8 last_accessible_byte = addr & ASAN_SHADOW_MASK;
                return unlikely(last_accessible_byte >= shadow_value);
        }
 
        return false;
}
 
static __always_inline bool memory_is_poisoned_2_4_8(unsigned long addr,
                                                unsigned long size)
{
        u8 *shadow_addr = (u8 *)asan_mem_to_shadow((void *)addr);
 
        if (unlikely(((addr + size - 1) & ASAN_SHADOW_MASK) < size - 1))
                return *shadow_addr || memory_is_poisoned_1(addr + size - 1);
 
        return memory_is_poisoned_1(addr + size - 1);
}
 
static __always_inline bool memory_is_poisoned_16(unsigned long addr)
{
        u16 *shadow_addr = (u16 *)asan_mem_to_shadow((void *)addr);
 
        if (unlikely(!IS_ALIGNED(addr, ASAN_SHADOW_SCALE_SIZE)))
                return *shadow_addr || memory_is_poisoned_1(addr + 15);
 
        return *shadow_addr;
}
 
static __always_inline unsigned long bytes_is_nonzero(const u8 *start,
                                        size_t size)
{
        while (size) {
                if (unlikely(*start))
                        return (unsigned long)start;
                start++;
                size--;
        }
 
        return 0;
}
 
static __always_inline unsigned long memory_is_nonzero(const void *start,
                                                const void *end)
{
        unsigned int words;
        unsigned long ret;
        unsigned int prefix = (unsigned long)start % 8;
 
        if (end - start <= 16)
                return bytes_is_nonzero(start, end - start);
 
        if (prefix) {
                prefix = 8 - prefix;
                ret = bytes_is_nonzero(start, prefix);
                if (unlikely(ret))
                        return ret;
                start += prefix;
        }
 
        words = (end - start) / 8;
        while (words) {
                if (unlikely(*(u64 *)start))
                        return bytes_is_nonzero(start, 8);
                start += 8;
                words--;
        }
 
        return bytes_is_nonzero(start, (end - start) % 8);
}
 
static __always_inline bool memory_is_poisoned_n(unsigned long addr,
                                                size_t size)
{
        unsigned long ret;
 
        ret = memory_is_nonzero(asan_mem_to_shadow((void *)addr),
                        asan_mem_to_shadow((void *)addr + size - 1) + 1);
 
        if (unlikely(ret)) {
                unsigned long last_byte = addr + size - 1;
                s8 *last_shadow = (s8 *)asan_mem_to_shadow((void *)last_byte);
 
                if (unlikely(ret != (unsigned long)last_shadow ||
                        ((long)(last_byte & ASAN_SHADOW_MASK) >= *last_shadow)))
                        return true;
        }
        return false;
}
 
static __always_inline bool memory_is_poisoned(unsigned long addr, size_t size)
{
        if (__builtin_constant_p(size)) {
                switch (size) {
                case 1:
                        return memory_is_poisoned_1(addr);
                case 2:
                case 4:
                case 8:
                        return memory_is_poisoned_2_4_8(addr, size);
                case 16:
                        return memory_is_poisoned_16(addr);
                default:
                        assert(0);
                }
        }
 
        return memory_is_poisoned_n(addr, size);
}
 
static const void *find_first_bad_addr(const void *addr, size_t size)
{
        u8 shadow_val = *(u8 *)asan_mem_to_shadow(addr);
        const void *first_bad_addr = addr;
 
        while (!shadow_val && first_bad_addr < addr + size) {
                first_bad_addr += ASAN_SHADOW_SCALE_SIZE;
                shadow_val = *(u8 *)asan_mem_to_shadow(first_bad_addr);
        }
        return first_bad_addr;
}
 
static const char *get_shadow_bug_type(const void *addr, size_t size)
{
        const char *bug_type = "unknown-crash";
        u8 *shadow_addr;
        const void *first_bad_addr;
 
        if (addr < asan_shadow_to_mem((void *) &_asan_shadow))
                return bug_type;
 
        first_bad_addr = find_first_bad_addr(addr, size);
 
        shadow_addr = (u8 *)asan_mem_to_shadow(first_bad_addr);
 
        if (*shadow_addr > 0 && *shadow_addr <= ASAN_SHADOW_SCALE_SIZE - 1)
                shadow_addr++;
 
        switch (*shadow_addr) {
        case 0 ... ASAN_SHADOW_SCALE_SIZE - 1:
                bug_type = "out-of-bounds";
                break;
        case ASAN_GLOBAL_REDZONE:
                bug_type = "global-out-of-bounds";
                break;
        case ASAN_STACK_LEFT:
        case ASAN_STACK_MID:
        case ASAN_STACK_RIGHT:
        case ASAN_STACK_PARTIAL:
                bug_type = "stack-out-of-bounds";
                break;
        case ASAN_USE_AFTER_SCOPE:
                bug_type = "use-after-scope";
                break;
        default:
                bug_type = "unknown-crash";
        }
 
        return bug_type;
}
 
void asan_report(unsigned long addr, size_t size, bool is_write,
        unsigned long ip)
{
        const char *bug_type = get_shadow_bug_type((void *) addr, size);
        printk(BIOS_ERR, "\n");
        printk(BIOS_ERR, "ASan: %s in %p\n", bug_type, (void *) ip);
        printk(BIOS_ERR, "%s of %zu byte%s at addr %p\n",
                is_write ? "Write" : "Read", size, (size > 1 ? "s" : ""),
                (void *) addr);
        printk(BIOS_ERR, "\n");
}
 
static __always_inline void check_memory_region_inline(unsigned long addr,
                                                size_t size, bool write,
                                                unsigned long ret_ip)
{
#if ENV_ROMSTAGE
        if (((uintptr_t)addr < (uintptr_t)&_car_region_start) ||
                ((uintptr_t)addr > (uintptr_t)&_ebss))
                return;
#elif ENV_RAMSTAGE
        if (((uintptr_t)addr < (uintptr_t)&_data) ||
                ((uintptr_t)addr > (uintptr_t)&_eheap))
                return;
#endif
        if (unlikely(size == 0))
                return;
 
        if (unlikely((void *)addr <
                asan_shadow_to_mem((void *) &_asan_shadow))) {
                asan_report(addr, size, write, ret_ip);
                return;
        }
 
        if (likely(!memory_is_poisoned(addr, size)))
                return;
 
        asan_report(addr, size, write, ret_ip);
}
 
void check_memory_region(unsigned long addr, size_t size, bool write,
                                unsigned long ret_ip)
{
        check_memory_region_inline(addr, size, write, ret_ip);
}
 
uintptr_t __asan_shadow_offset(uintptr_t addr)
{
#if ENV_ROMSTAGE
        return (uintptr_t)&_asan_shadow - (((uintptr_t)&_car_region_start) >>
                ASAN_SHADOW_SCALE_SHIFT);
#elif ENV_RAMSTAGE
        return (uintptr_t)&_asan_shadow - (((uintptr_t)&_data) >>
                ASAN_SHADOW_SCALE_SHIFT);
#endif
}
 
static void register_global(struct asan_global *global)
{
        size_t aligned_size = ALIGN_UP(global->size, ASAN_SHADOW_SCALE_SIZE);
 
        asan_unpoison_shadow(global->beg, global->size);
 
        asan_poison_shadow(global->beg + aligned_size,
                global->size_with_redzone - aligned_size,
                ASAN_GLOBAL_REDZONE);
}
 
void __asan_register_globals(struct asan_global *globals, size_t size)
{
        int i;
 
        for (i = 0; i < size; i++)
                register_global(&globals[i]);
}
 
void __asan_unregister_globals(struct asan_global *globals, size_t size)
{
}
 
/*
 * GCC adds constructors invoking __asan_register_globals() and passes
 * information about global variable (address, size, size with redzone ...)
 * to it so we could poison variable's redzone.
 * This function calls those constructors.
 */
#if ENV_RAMSTAGE
static void asan_ctors(void)
{
        extern long __CTOR_LIST__;
        typedef void (*func_ptr)(void);
        func_ptr *ctor = (func_ptr *) &__CTOR_LIST__;
        if (ctor == NULL)
                return;
 
        for (; *ctor != (func_ptr) 0; ctor++)
                (*ctor)();
}
#endif
 
void asan_init(void)
{
#if ENV_ROMSTAGE
        size_t size = (size_t)&_ebss - (size_t)&_car_region_start;
        asan_unpoison_shadow((void *)&_car_region_start, size);
#elif ENV_RAMSTAGE
        size_t size = (size_t)&_eheap - (size_t)&_data;
        asan_unpoison_shadow((void *)&_data, size);
        asan_ctors();
#endif
}
 
void __asan_poison_stack_memory(const void *addr, size_t size)
{
        asan_poison_shadow(addr, ALIGN_UP(size, ASAN_SHADOW_SCALE_SIZE),
                            ASAN_USE_AFTER_SCOPE);
}
 
void __asan_unpoison_stack_memory(const void *addr, size_t size)
{
        asan_unpoison_shadow(addr, size);
}
 
#define DEFINE_ASAN_LOAD_STORE(size)    \
        void __asan_load##size(unsigned long addr)      \
        {       \
                check_memory_region_inline(addr, size, false, _RET_IP_);\
        }       \
        void __asan_load##size##_noabort(unsigned long addr)    \
        {       \
                check_memory_region_inline(addr, size, false, _RET_IP_);\
        }       \
        void __asan_store##size(unsigned long addr)     \
        {       \
                check_memory_region_inline(addr, size, true, _RET_IP_); \
        }       \
        void __asan_store##size##_noabort(unsigned long addr)   \
        {       \
                check_memory_region_inline(addr, size, true, _RET_IP_); \
        }
 
DEFINE_ASAN_LOAD_STORE(1);
DEFINE_ASAN_LOAD_STORE(2);
DEFINE_ASAN_LOAD_STORE(4);
DEFINE_ASAN_LOAD_STORE(8);
DEFINE_ASAN_LOAD_STORE(16);
 
void __asan_loadN(unsigned long addr, size_t size)
{
        check_memory_region(addr, size, false, _RET_IP_);
}
 
void __asan_storeN(unsigned long addr, size_t size)
{
        check_memory_region(addr, size, true, _RET_IP_);
}
 
void __asan_loadN_noabort(unsigned long addr, size_t size)
{
        check_memory_region(addr, size, false, _RET_IP_);
}
 
void __asan_storeN_noabort(unsigned long addr, size_t size)
{
        check_memory_region(addr, size, true, _RET_IP_);
}
 
void __asan_handle_no_return(void)
{
}
 
#define DEFINE_ASAN_SET_SHADOW(byte)    \
        void __asan_set_shadow_##byte(const void *addr, size_t size)    \
        {       \
                __builtin_memset((void *)addr, 0x##byte, size); \
        }
 
DEFINE_ASAN_SET_SHADOW(00);
DEFINE_ASAN_SET_SHADOW(f1);
DEFINE_ASAN_SET_SHADOW(f2);
DEFINE_ASAN_SET_SHADOW(f3);
DEFINE_ASAN_SET_SHADOW(f5);
DEFINE_ASAN_SET_SHADOW(f8);
 
#define DEFINE_ASAN_REPORT_LOAD(size)   \
void __asan_report_load##size##_noabort(unsigned long addr)     \
{       \
        asan_report(addr, size, false, _RET_IP_);       \
}
 
#define DEFINE_ASAN_REPORT_STORE(size)  \
void __asan_report_store##size##_noabort(unsigned long addr)    \
{       \
        asan_report(addr, size, true, _RET_IP_);        \
}
 
DEFINE_ASAN_REPORT_LOAD(1);
DEFINE_ASAN_REPORT_LOAD(2);
DEFINE_ASAN_REPORT_LOAD(4);
DEFINE_ASAN_REPORT_LOAD(8);
DEFINE_ASAN_REPORT_LOAD(16);
DEFINE_ASAN_REPORT_STORE(1);
DEFINE_ASAN_REPORT_STORE(2);
DEFINE_ASAN_REPORT_STORE(4);
DEFINE_ASAN_REPORT_STORE(8);
DEFINE_ASAN_REPORT_STORE(16);
 
void __asan_report_load_n_noabort(unsigned long addr, size_t size)
{
        asan_report(addr, size, false, _RET_IP_);
}
 
void __asan_report_store_n_noabort(unsigned long addr, size_t size)
{
        asan_report(addr, size, true, _RET_IP_);
}