diff options
Diffstat (limited to 'lib/kasan/report.c')
| -rw-r--r-- | lib/kasan/report.c | 199 |
1 files changed, 199 insertions, 0 deletions
diff --git a/lib/kasan/report.c b/lib/kasan/report.c new file mode 100644 index 0000000000..b7b2d032ee --- /dev/null +++ b/lib/kasan/report.c @@ -0,0 +1,199 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * This file contains common generic and tag-based KASAN error reporting code. + * + * Copyright (c) 2014 Samsung Electronics Co., Ltd. + * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com> + * + * Some code borrowed from https://github.com/xairy/kasan-prototype by + * Andrey Konovalov <andreyknvl@gmail.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + */ + +#include <common.h> +#include <linux/bitops.h> +#include <linux/kernel.h> +#include <printk.h> +#include <asm-generic/sections.h> + +#include "kasan.h" + +/* Shadow layout customization. */ +#define SHADOW_BYTES_PER_BLOCK 1 +#define SHADOW_BLOCKS_PER_ROW 16 +#define SHADOW_BYTES_PER_ROW (SHADOW_BLOCKS_PER_ROW * SHADOW_BYTES_PER_BLOCK) +#define SHADOW_ROWS_AROUND_ADDR 2 + +static unsigned long kasan_flags; + +#define KASAN_BIT_REPORTED 0 +#define KASAN_BIT_MULTI_SHOT 1 + +bool kasan_save_enable_multi_shot(void) +{ + return test_and_set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags); +} +EXPORT_SYMBOL_GPL(kasan_save_enable_multi_shot); + +void kasan_restore_multi_shot(bool enabled) +{ + if (!enabled) + clear_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags); +} +EXPORT_SYMBOL_GPL(kasan_restore_multi_shot); + +static void print_error_description(struct kasan_access_info *info) +{ + pr_err("BUG: KASAN: %s in %pS\n", + get_bug_type(info), (void *)info->ip); + pr_err("%s of size %zu at addr %px\n", + info->is_write ? "Write" : "Read", info->access_size, + info->access_addr); +} + +static void start_report(unsigned long *flags) +{ + /* + * Make sure we don't end up in loop. + */ + kasan_disable_current(); + pr_err("==================================================================\n"); +} + +static void end_report(unsigned long *flags) +{ + pr_err("==================================================================\n"); + kasan_enable_current(); +} + +static inline bool kernel_or_module_addr(const void *addr) +{ + if (addr >= (void *)_stext && addr < (void *)_end) + return true; + return false; +} + +static void print_address_description(void *addr, u8 tag) +{ + dump_stack(); + pr_err("\n"); + + if (kernel_or_module_addr(addr)) { + pr_err("The buggy address belongs to the variable:\n"); + pr_err(" %pS\n", addr); + } +} + +static bool row_is_guilty(const void *row, const void *guilty) +{ + return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW); +} + +static int shadow_pointer_offset(const void *row, const void *shadow) +{ + /* The length of ">ff00ff00ff00ff00: " is + * 3 + (BITS_PER_LONG/8)*2 chars. + */ + return 3 + (BITS_PER_LONG/8)*2 + (shadow - row)*2 + + (shadow - row) / SHADOW_BYTES_PER_BLOCK + 1; +} + +static void print_shadow_for_address(const void *addr) +{ + int i; + const void *shadow = kasan_mem_to_shadow(addr); + const void *shadow_row; + + shadow_row = (void *)round_down((unsigned long)shadow, + SHADOW_BYTES_PER_ROW) + - SHADOW_ROWS_AROUND_ADDR * SHADOW_BYTES_PER_ROW; + + pr_err("Memory state around the buggy address:\n"); + + for (i = -SHADOW_ROWS_AROUND_ADDR; i <= SHADOW_ROWS_AROUND_ADDR; i++) { + const void *kaddr = kasan_shadow_to_mem(shadow_row); + char buffer[4 + (BITS_PER_LONG/8)*2]; + char shadow_buf[SHADOW_BYTES_PER_ROW]; + + snprintf(buffer, sizeof(buffer), + (i == 0) ? ">%px: " : " %px: ", kaddr); + /* + * We should not pass a shadow pointer to generic + * function, because generic functions may try to + * access kasan mapping for the passed address. + */ + memcpy(shadow_buf, shadow_row, SHADOW_BYTES_PER_ROW); + print_hex_dump(KERN_ERR, buffer, + DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1, + shadow_buf, SHADOW_BYTES_PER_ROW, 0); + + if (row_is_guilty(shadow_row, shadow)) + printf("%*c\n", + shadow_pointer_offset(shadow_row, shadow), + '^'); + + shadow_row += SHADOW_BYTES_PER_ROW; + } +} + +static bool report_enabled(void) +{ + if (kasan_depth) + return false; + if (test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags)) + return true; + return !test_and_set_bit(KASAN_BIT_REPORTED, &kasan_flags); +} + +static void __kasan_report(unsigned long addr, size_t size, bool is_write, + unsigned long ip) +{ + struct kasan_access_info info; + void *tagged_addr; + void *untagged_addr; + unsigned long flags; + + tagged_addr = (void *)addr; + untagged_addr = reset_tag(tagged_addr); + + info.access_addr = tagged_addr; + if (addr_has_shadow(untagged_addr)) + info.first_bad_addr = find_first_bad_addr(tagged_addr, size); + else + info.first_bad_addr = untagged_addr; + info.access_size = size; + info.is_write = is_write; + info.ip = ip; + + start_report(&flags); + + print_error_description(&info); + pr_err("\n"); + + if (addr_has_shadow(untagged_addr)) { + print_address_description(untagged_addr, get_tag(tagged_addr)); + pr_err("\n"); + print_shadow_for_address(info.first_bad_addr); + } else { + dump_stack(); + } + + end_report(&flags); +} + +bool kasan_report(unsigned long addr, size_t size, bool is_write, + unsigned long ip) +{ + bool ret = false; + + if (likely(report_enabled())) { + __kasan_report(addr, size, is_write, ip); + ret = true; + } + + return ret; +} |