diff options
Diffstat (limited to 'mm/kasan/report.c')
| -rw-r--r-- | mm/kasan/report.c | 828 |
1 files changed, 463 insertions, 365 deletions
diff --git a/mm/kasan/report.c b/mm/kasan/report.c index 51ec45407a0b..62c01b4527eb 100644 --- a/mm/kasan/report.c +++ b/mm/kasan/report.c @@ -1,23 +1,21 @@ // SPDX-License-Identifier: GPL-2.0 /* - * This file contains common generic and tag-based KASAN error reporting code. + * This file contains common 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 <kunit/test.h> +#include <kunit/visibility.h> #include <linux/bitops.h> #include <linux/ftrace.h> #include <linux/init.h> #include <linux/kernel.h> +#include <linux/lockdep.h> #include <linux/mm.h> #include <linux/printk.h> #include <linux/sched.h> @@ -26,39 +24,50 @@ #include <linux/stacktrace.h> #include <linux/string.h> #include <linux/types.h> +#include <linux/vmalloc.h> #include <linux/kasan.h> #include <linux/module.h> #include <linux/sched/task_stack.h> #include <linux/uaccess.h> +#include <trace/events/error_report.h> #include <asm/sections.h> #include "kasan.h" #include "../slab.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); +enum kasan_arg_fault { + KASAN_ARG_FAULT_DEFAULT, + KASAN_ARG_FAULT_REPORT, + KASAN_ARG_FAULT_PANIC, + KASAN_ARG_FAULT_PANIC_ON_WRITE, +}; -void kasan_restore_multi_shot(bool enabled) +static enum kasan_arg_fault kasan_arg_fault __ro_after_init = KASAN_ARG_FAULT_DEFAULT; + +/* kasan.fault=report/panic */ +static int __init early_kasan_fault(char *arg) { - if (!enabled) - clear_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags); + if (!arg) + return -EINVAL; + + if (!strcmp(arg, "report")) + kasan_arg_fault = KASAN_ARG_FAULT_REPORT; + else if (!strcmp(arg, "panic")) + kasan_arg_fault = KASAN_ARG_FAULT_PANIC; + else if (!strcmp(arg, "panic_on_write")) + kasan_arg_fault = KASAN_ARG_FAULT_PANIC_ON_WRITE; + else + return -EINVAL; + + return 0; } -EXPORT_SYMBOL_GPL(kasan_restore_multi_shot); +early_param("kasan.fault", early_kasan_fault); static int __init kasan_set_multi_shot(char *str) { @@ -67,511 +76,600 @@ static int __init kasan_set_multi_shot(char *str) } __setup("kasan_multi_shot", kasan_set_multi_shot); -static void print_error_description(struct kasan_access_info *info) +/* + * This function is used to check whether KASAN reports are suppressed for + * software KASAN modes via kasan_disable/enable_current() critical sections. + * + * This is done to avoid: + * 1. False-positive reports when accessing slab metadata, + * 2. Deadlocking when poisoned memory is accessed by the reporting code. + * + * Hardware Tag-Based KASAN instead relies on: + * For #1: Resetting tags via kasan_reset_tag(). + * For #2: Suppression of tag checks via CPU, see report_suppress_start/end(). + */ +static bool report_suppressed_sw(void) { - pr_err("BUG: KASAN: %s in %pS\n", - get_bug_type(info), (void *)info->ip); - pr_err("%s of size %zu at addr %px by task %s/%d\n", - info->is_write ? "Write" : "Read", info->access_size, - info->access_addr, current->comm, task_pid_nr(current)); +#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS) + if (current->kasan_depth) + return true; +#endif + return false; } -static DEFINE_SPINLOCK(report_lock); - -static void start_report(unsigned long *flags) +static void report_suppress_start(void) { +#ifdef CONFIG_KASAN_HW_TAGS /* - * Make sure we don't end up in loop. + * Disable preemption for the duration of printing a KASAN report, as + * hw_suppress_tag_checks_start() disables checks on the current CPU. */ + preempt_disable(); + hw_suppress_tag_checks_start(); +#else kasan_disable_current(); - spin_lock_irqsave(&report_lock, *flags); - pr_err("==================================================================\n"); +#endif } -static void end_report(unsigned long *flags) +static void report_suppress_stop(void) { - pr_err("==================================================================\n"); - add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); - spin_unlock_irqrestore(&report_lock, *flags); - if (panic_on_warn) { - /* - * This thread may hit another WARN() in the panic path. - * Resetting this prevents additional WARN() from panicking the - * system on this thread. Other threads are blocked by the - * panic_mutex in panic(). - */ - panic_on_warn = 0; - panic("panic_on_warn set ...\n"); - } +#ifdef CONFIG_KASAN_HW_TAGS + hw_suppress_tag_checks_stop(); + preempt_enable(); +#else kasan_enable_current(); +#endif } -static void print_track(struct kasan_track *track, const char *prefix) +/* + * Used to avoid reporting more than one KASAN bug unless kasan_multi_shot + * is enabled. Note that KASAN tests effectively enable kasan_multi_shot + * for their duration. + */ +static bool report_enabled(void) { - pr_err("%s by task %u:\n", prefix, track->pid); - if (track->stack) { - unsigned long *entries; - unsigned int nr_entries; - - nr_entries = stack_depot_fetch(track->stack, &entries); - stack_trace_print(entries, nr_entries, 0); - } else { - pr_err("(stack is not available)\n"); - } + if (test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags)) + return true; + return !test_and_set_bit(KASAN_BIT_REPORTED, &kasan_flags); } -struct page *kasan_addr_to_page(const void *addr) +#if IS_ENABLED(CONFIG_KASAN_KUNIT_TEST) + +VISIBLE_IF_KUNIT bool kasan_save_enable_multi_shot(void) { - if ((addr >= (void *)PAGE_OFFSET) && - (addr < high_memory)) - return virt_to_head_page(addr); - return NULL; + return test_and_set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags); } +EXPORT_SYMBOL_IF_KUNIT(kasan_save_enable_multi_shot); -static void describe_object_addr(struct kmem_cache *cache, void *object, - const void *addr) +VISIBLE_IF_KUNIT void kasan_restore_multi_shot(bool enabled) { - unsigned long access_addr = (unsigned long)addr; - unsigned long object_addr = (unsigned long)object; - const char *rel_type; - int rel_bytes; + if (!enabled) + clear_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags); +} +EXPORT_SYMBOL_IF_KUNIT(kasan_restore_multi_shot); - pr_err("The buggy address belongs to the object at %px\n" - " which belongs to the cache %s of size %d\n", - object, cache->name, cache->object_size); +#endif - if (!addr) - return; +#if IS_ENABLED(CONFIG_KASAN_KUNIT_TEST) - if (access_addr < object_addr) { - rel_type = "to the left"; - rel_bytes = object_addr - access_addr; - } else if (access_addr >= object_addr + cache->object_size) { - rel_type = "to the right"; - rel_bytes = access_addr - (object_addr + cache->object_size); - } else { - rel_type = "inside"; - rel_bytes = access_addr - object_addr; - } +/* + * Whether the KASAN KUnit test suite is currently being executed. + * Updated in kasan_test.c. + */ +static bool kasan_kunit_executing; - pr_err("The buggy address is located %d bytes %s of\n" - " %d-byte region [%px, %px)\n", - rel_bytes, rel_type, cache->object_size, (void *)object_addr, - (void *)(object_addr + cache->object_size)); +VISIBLE_IF_KUNIT void kasan_kunit_test_suite_start(void) +{ + WRITE_ONCE(kasan_kunit_executing, true); } +EXPORT_SYMBOL_IF_KUNIT(kasan_kunit_test_suite_start); -static struct kasan_track *kasan_get_free_track(struct kmem_cache *cache, - void *object, u8 tag) +VISIBLE_IF_KUNIT void kasan_kunit_test_suite_end(void) { - struct kasan_alloc_meta *alloc_meta; - int i = 0; - - alloc_meta = get_alloc_info(cache, object); - -#ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY - for (i = 0; i < KASAN_NR_FREE_STACKS; i++) { - if (alloc_meta->free_pointer_tag[i] == tag) - break; - } - if (i == KASAN_NR_FREE_STACKS) - i = alloc_meta->free_track_idx; -#endif - - return &alloc_meta->free_track[i]; + WRITE_ONCE(kasan_kunit_executing, false); } +EXPORT_SYMBOL_IF_KUNIT(kasan_kunit_test_suite_end); -static void describe_object(struct kmem_cache *cache, void *object, - const void *addr, u8 tag) +static bool kasan_kunit_test_suite_executing(void) { - struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object); + return READ_ONCE(kasan_kunit_executing); +} - if (cache->flags & SLAB_KASAN) { - struct kasan_track *free_track; +#else /* CONFIG_KASAN_KUNIT_TEST */ - print_track(&alloc_info->alloc_track, "Allocated"); - pr_err("\n"); - free_track = kasan_get_free_track(cache, object, tag); - print_track(free_track, "Freed"); - pr_err("\n"); - } +static inline bool kasan_kunit_test_suite_executing(void) { return false; } - describe_object_addr(cache, object, addr); -} +#endif /* CONFIG_KASAN_KUNIT_TEST */ -static inline bool kernel_or_module_addr(const void *addr) -{ - if (addr >= (void *)_stext && addr < (void *)_end) - return true; - if (is_module_address((unsigned long)addr)) - return true; - return false; -} +#if IS_ENABLED(CONFIG_KUNIT) -static inline bool init_task_stack_addr(const void *addr) +static void fail_non_kasan_kunit_test(void) { - return addr >= (void *)&init_thread_union.stack && - (addr <= (void *)&init_thread_union.stack + - sizeof(init_thread_union.stack)); + struct kunit *test; + + if (kasan_kunit_test_suite_executing()) + return; + + test = current->kunit_test; + if (test) + kunit_set_failure(test); } -static bool __must_check tokenize_frame_descr(const char **frame_descr, - char *token, size_t max_tok_len, - unsigned long *value) -{ - const char *sep = strchr(*frame_descr, ' '); +#else /* CONFIG_KUNIT */ + +static inline void fail_non_kasan_kunit_test(void) { } - if (sep == NULL) - sep = *frame_descr + strlen(*frame_descr); +#endif /* CONFIG_KUNIT */ - if (token != NULL) { - const size_t tok_len = sep - *frame_descr; +static DEFINE_RAW_SPINLOCK(report_lock); - if (tok_len + 1 > max_tok_len) { - pr_err("KASAN internal error: frame description too long: %s\n", - *frame_descr); - return false; - } +static void start_report(unsigned long *flags, bool sync) +{ + fail_non_kasan_kunit_test(); + /* Respect the /proc/sys/kernel/traceoff_on_warning interface. */ + disable_trace_on_warning(); + /* Do not allow LOCKDEP mangling KASAN reports. */ + lockdep_off(); + /* Make sure we don't end up in loop. */ + report_suppress_start(); + raw_spin_lock_irqsave(&report_lock, *flags); + pr_err("==================================================================\n"); +} - /* Copy token (+ 1 byte for '\0'). */ - strlcpy(token, *frame_descr, tok_len + 1); +static void end_report(unsigned long *flags, const void *addr, bool is_write) +{ + if (addr) + trace_error_report_end(ERROR_DETECTOR_KASAN, + (unsigned long)addr); + pr_err("==================================================================\n"); + raw_spin_unlock_irqrestore(&report_lock, *flags); + if (!test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags)) + check_panic_on_warn("KASAN"); + switch (kasan_arg_fault) { + case KASAN_ARG_FAULT_DEFAULT: + case KASAN_ARG_FAULT_REPORT: + break; + case KASAN_ARG_FAULT_PANIC: + panic("kasan.fault=panic set ...\n"); + break; + case KASAN_ARG_FAULT_PANIC_ON_WRITE: + if (is_write) + panic("kasan.fault=panic_on_write set ...\n"); + break; } + add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); + lockdep_on(); + report_suppress_stop(); +} - /* Advance frame_descr past separator. */ - *frame_descr = sep + 1; +static void print_error_description(struct kasan_report_info *info) +{ + pr_err("BUG: KASAN: %s in %pS\n", info->bug_type, (void *)info->ip); - if (value != NULL && kstrtoul(token, 10, value)) { - pr_err("KASAN internal error: not a valid number: %s\n", token); - return false; + if (info->type != KASAN_REPORT_ACCESS) { + pr_err("Free of addr %px by task %s/%d\n", + info->access_addr, current->comm, task_pid_nr(current)); + return; } - return true; + if (info->access_size) + pr_err("%s of size %zu at addr %px by task %s/%d\n", + info->is_write ? "Write" : "Read", info->access_size, + info->access_addr, current->comm, task_pid_nr(current)); + else + pr_err("%s at addr %px by task %s/%d\n", + info->is_write ? "Write" : "Read", + info->access_addr, current->comm, task_pid_nr(current)); } -static void print_decoded_frame_descr(const char *frame_descr) +static void print_track(struct kasan_track *track, const char *prefix) { - /* - * We need to parse the following string: - * "n alloc_1 alloc_2 ... alloc_n" - * where alloc_i looks like - * "offset size len name" - * or "offset size len name:line". - */ +#ifdef CONFIG_KASAN_EXTRA_INFO + u64 ts_nsec = track->timestamp; + unsigned long rem_usec; - char token[64]; - unsigned long num_objects; + ts_nsec <<= 9; + rem_usec = do_div(ts_nsec, NSEC_PER_SEC) / 1000; - if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), - &num_objects)) - return; - - pr_err("\n"); - pr_err("this frame has %lu %s:\n", num_objects, - num_objects == 1 ? "object" : "objects"); - - while (num_objects--) { - unsigned long offset; - unsigned long size; - - /* access offset */ - if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), - &offset)) - return; - /* access size */ - if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), - &size)) - return; - /* name length (unused) */ - if (!tokenize_frame_descr(&frame_descr, NULL, 0, NULL)) - return; - /* object name */ - if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), - NULL)) - return; - - /* Strip line number; without filename it's not very helpful. */ - strreplace(token, ':', '\0'); - - /* Finally, print object information. */ - pr_err(" [%lu, %lu) '%s'", offset, offset + size, token); - } + pr_err("%s by task %u on cpu %d at %lu.%06lus:\n", + prefix, track->pid, track->cpu, + (unsigned long)ts_nsec, rem_usec); +#else + pr_err("%s by task %u:\n", prefix, track->pid); +#endif /* CONFIG_KASAN_EXTRA_INFO */ + if (track->stack) + stack_depot_print(track->stack); + else + pr_err("(stack is not available)\n"); } -static bool __must_check get_address_stack_frame_info(const void *addr, - unsigned long *offset, - const char **frame_descr, - const void **frame_pc) +static inline struct page *addr_to_page(const void *addr) { - unsigned long aligned_addr; - unsigned long mem_ptr; - const u8 *shadow_bottom; - const u8 *shadow_ptr; - const unsigned long *frame; - - BUILD_BUG_ON(IS_ENABLED(CONFIG_STACK_GROWSUP)); + if (virt_addr_valid(addr)) + return virt_to_head_page(addr); + return NULL; +} - /* - * NOTE: We currently only support printing frame information for - * accesses to the task's own stack. - */ - if (!object_is_on_stack(addr)) - return false; +static void describe_object_addr(const void *addr, struct kasan_report_info *info) +{ + unsigned long access_addr = (unsigned long)addr; + unsigned long object_addr = (unsigned long)info->object; + const char *rel_type, *region_state = ""; + int rel_bytes; - aligned_addr = round_down((unsigned long)addr, sizeof(long)); - mem_ptr = round_down(aligned_addr, KASAN_SHADOW_SCALE_SIZE); - shadow_ptr = kasan_mem_to_shadow((void *)aligned_addr); - shadow_bottom = kasan_mem_to_shadow(end_of_stack(current)); + pr_err("The buggy address belongs to the object at %px\n" + " which belongs to the cache %s of size %d\n", + info->object, info->cache->name, info->cache->object_size); - while (shadow_ptr >= shadow_bottom && *shadow_ptr != KASAN_STACK_LEFT) { - shadow_ptr--; - mem_ptr -= KASAN_SHADOW_SCALE_SIZE; + if (access_addr < object_addr) { + rel_type = "to the left"; + rel_bytes = object_addr - access_addr; + } else if (access_addr >= object_addr + info->alloc_size) { + rel_type = "to the right"; + rel_bytes = access_addr - (object_addr + info->alloc_size); + } else { + rel_type = "inside"; + rel_bytes = access_addr - object_addr; } - while (shadow_ptr >= shadow_bottom && *shadow_ptr == KASAN_STACK_LEFT) { - shadow_ptr--; - mem_ptr -= KASAN_SHADOW_SCALE_SIZE; + /* + * Tag-Based modes use the stack ring to infer the bug type, but the + * memory region state description is generated based on the metadata. + * Thus, defining the region state as below can contradict the metadata. + * Fixing this requires further improvements, so only infer the state + * for the Generic mode. + */ + if (IS_ENABLED(CONFIG_KASAN_GENERIC)) { + if (strcmp(info->bug_type, "slab-out-of-bounds") == 0) + region_state = "allocated "; + else if (strcmp(info->bug_type, "slab-use-after-free") == 0) + region_state = "freed "; } - if (shadow_ptr < shadow_bottom) - return false; + pr_err("The buggy address is located %d bytes %s of\n" + " %s%zu-byte region [%px, %px)\n", + rel_bytes, rel_type, region_state, info->alloc_size, + (void *)object_addr, (void *)(object_addr + info->alloc_size)); +} - frame = (const unsigned long *)(mem_ptr + KASAN_SHADOW_SCALE_SIZE); - if (frame[0] != KASAN_CURRENT_STACK_FRAME_MAGIC) { - pr_err("KASAN internal error: frame info validation failed; invalid marker: %lu\n", - frame[0]); - return false; +static void describe_object_stacks(struct kasan_report_info *info) +{ + if (info->alloc_track.stack) { + print_track(&info->alloc_track, "Allocated"); + pr_err("\n"); } - *offset = (unsigned long)addr - (unsigned long)frame; - *frame_descr = (const char *)frame[1]; - *frame_pc = (void *)frame[2]; + if (info->free_track.stack) { + print_track(&info->free_track, "Freed"); + pr_err("\n"); + } - return true; + kasan_print_aux_stacks(info->cache, info->object); } -static void print_address_stack_frame(const void *addr) +static void describe_object(const void *addr, struct kasan_report_info *info) { - unsigned long offset; - const char *frame_descr; - const void *frame_pc; - - if (IS_ENABLED(CONFIG_KASAN_SW_TAGS)) - return; - - if (!get_address_stack_frame_info(addr, &offset, &frame_descr, - &frame_pc)) - return; - - /* - * get_address_stack_frame_info only returns true if the given addr is - * on the current task's stack. - */ - pr_err("\n"); - pr_err("addr %px is located in stack of task %s/%d at offset %lu in frame:\n", - addr, current->comm, task_pid_nr(current), offset); - pr_err(" %pS\n", frame_pc); + if (kasan_stack_collection_enabled()) + describe_object_stacks(info); + describe_object_addr(addr, info); +} - if (!frame_descr) - return; +static inline bool kernel_or_module_addr(const void *addr) +{ + if (is_kernel((unsigned long)addr)) + return true; + if (is_module_address((unsigned long)addr)) + return true; + return false; +} - print_decoded_frame_descr(frame_descr); +static inline bool init_task_stack_addr(const void *addr) +{ + return addr >= (void *)&init_thread_union.stack && + (addr <= (void *)&init_thread_union.stack + + sizeof(init_thread_union.stack)); } -static void print_address_description(void *addr, u8 tag) +static void print_address_description(void *addr, u8 tag, + struct kasan_report_info *info) { - struct page *page = kasan_addr_to_page(addr); + struct page *page = addr_to_page(addr); - dump_stack(); + dump_stack_lvl(KERN_ERR); pr_err("\n"); - if (page && PageSlab(page)) { - struct kmem_cache *cache = page->slab_cache; - void *object = nearest_obj(cache, page, addr); - - describe_object(cache, object, addr, tag); + if (info->cache && info->object) { + describe_object(addr, info); + pr_err("\n"); } if (kernel_or_module_addr(addr) && !init_task_stack_addr(addr)) { pr_err("The buggy address belongs to the variable:\n"); pr_err(" %pS\n", addr); + pr_err("\n"); + } + + if (object_is_on_stack(addr)) { + /* + * Currently, KASAN supports printing frame information only + * for accesses to the task's own stack. + */ + kasan_print_address_stack_frame(addr); + pr_err("\n"); + } + + if (is_vmalloc_addr(addr)) { + pr_err("The buggy address belongs to a"); + if (!vmalloc_dump_obj(addr)) + pr_cont(" vmalloc virtual mapping\n"); + page = vmalloc_to_page(addr); } if (page) { - pr_err("The buggy address belongs to the page:\n"); + pr_err("The buggy address belongs to the physical page:\n"); dump_page(page, "kasan: bad access detected"); + pr_err("\n"); } - - print_address_stack_frame(addr); } -static bool row_is_guilty(const void *row, const void *guilty) +static bool meta_row_is_guilty(const void *row, const void *addr) { - return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW); + return (row <= addr) && (addr < row + META_MEM_BYTES_PER_ROW); } -static int shadow_pointer_offset(const void *row, const void *shadow) +static int meta_pointer_offset(const void *row, const void *addr) { - /* The length of ">ff00ff00ff00ff00: " is - * 3 + (BITS_PER_LONG/8)*2 chars. + /* + * Memory state around the buggy address: + * ff00ff00ff00ff00: 00 00 00 05 fe fe fe fe fe fe fe fe fe fe fe fe + * ... + * + * The length of ">ff00ff00ff00ff00: " is + * 3 + (BITS_PER_LONG / 8) * 2 chars. + * The length of each granule metadata is 2 bytes + * plus 1 byte for space. */ - return 3 + (BITS_PER_LONG/8)*2 + (shadow - row)*2 + - (shadow - row) / SHADOW_BYTES_PER_BLOCK + 1; + return 3 + (BITS_PER_LONG / 8) * 2 + + (addr - row) / KASAN_GRANULE_SIZE * 3 + 1; } -static void print_shadow_for_address(const void *addr) +static void print_memory_metadata(const void *addr) { int i; - const void *shadow = kasan_mem_to_shadow(addr); - const void *shadow_row; + void *row; - shadow_row = (void *)round_down((unsigned long)shadow, - SHADOW_BYTES_PER_ROW) - - SHADOW_ROWS_AROUND_ADDR * SHADOW_BYTES_PER_ROW; + row = (void *)round_down((unsigned long)addr, META_MEM_BYTES_PER_ROW) + - META_ROWS_AROUND_ADDR * META_MEM_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]; + for (i = -META_ROWS_AROUND_ADDR; i <= META_ROWS_AROUND_ADDR; i++) { + char buffer[4 + (BITS_PER_LONG / 8) * 2]; + char metadata[META_BYTES_PER_ROW]; snprintf(buffer, sizeof(buffer), - (i == 0) ? ">%px: " : " %px: ", kaddr); + (i == 0) ? ">%px: " : " %px: ", row); + /* * 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); + kasan_metadata_fetch_row(&metadata[0], row); + print_hex_dump(KERN_ERR, buffer, - DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1, - shadow_buf, SHADOW_BYTES_PER_ROW, 0); + DUMP_PREFIX_NONE, META_BYTES_PER_ROW, 1, + metadata, META_BYTES_PER_ROW, 0); - if (row_is_guilty(shadow_row, shadow)) - pr_err("%*c\n", - shadow_pointer_offset(shadow_row, shadow), - '^'); + if (meta_row_is_guilty(row, addr)) + pr_err("%*c\n", meta_pointer_offset(row, addr), '^'); - shadow_row += SHADOW_BYTES_PER_ROW; + row += META_MEM_BYTES_PER_ROW; } } -static bool report_enabled(void) +static void print_report(struct kasan_report_info *info) { - if (current->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); + void *addr = kasan_reset_tag((void *)info->access_addr); + u8 tag = get_tag((void *)info->access_addr); + + print_error_description(info); + if (addr_has_metadata(addr)) + kasan_print_tags(tag, info->first_bad_addr); + pr_err("\n"); + + if (addr_has_metadata(addr)) { + print_address_description(addr, tag, info); + print_memory_metadata(info->first_bad_addr); + } else { + dump_stack_lvl(KERN_ERR); + } } -void kasan_report_invalid_free(void *object, unsigned long ip) +static void complete_report_info(struct kasan_report_info *info) { - unsigned long flags; - u8 tag = get_tag(object); + void *addr = kasan_reset_tag((void *)info->access_addr); + struct slab *slab; - object = reset_tag(object); - start_report(&flags); - pr_err("BUG: KASAN: double-free or invalid-free in %pS\n", (void *)ip); - print_tags(tag, object); - pr_err("\n"); - print_address_description(object, tag); - pr_err("\n"); - print_shadow_for_address(object); - end_report(&flags); + if (info->type == KASAN_REPORT_ACCESS) + info->first_bad_addr = kasan_find_first_bad_addr( + (void *)info->access_addr, info->access_size); + else + info->first_bad_addr = addr; + + slab = kasan_addr_to_slab(addr); + if (slab) { + info->cache = slab->slab_cache; + info->object = nearest_obj(info->cache, slab, addr); + + /* Try to determine allocation size based on the metadata. */ + info->alloc_size = kasan_get_alloc_size(info->object, info->cache); + /* Fallback to the object size if failed. */ + if (!info->alloc_size) + info->alloc_size = info->cache->object_size; + } else + info->cache = info->object = NULL; + + switch (info->type) { + case KASAN_REPORT_INVALID_FREE: + info->bug_type = "invalid-free"; + break; + case KASAN_REPORT_DOUBLE_FREE: + info->bug_type = "double-free"; + break; + default: + /* bug_type filled in by kasan_complete_mode_report_info. */ + break; + } + + /* Fill in mode-specific report info fields. */ + kasan_complete_mode_report_info(info); } -static void __kasan_report(unsigned long addr, size_t size, bool is_write, - unsigned long ip) +void kasan_report_invalid_free(void *ptr, unsigned long ip, enum kasan_report_type type) { - struct kasan_access_info info; - void *tagged_addr; - void *untagged_addr; unsigned long flags; + struct kasan_report_info info; - disable_trace_on_warning(); + /* + * Do not check report_suppressed_sw(), as an invalid-free cannot be + * caused by accessing poisoned memory and thus should not be suppressed + * by kasan_disable/enable_current() critical sections. + * + * Note that for Hardware Tag-Based KASAN, kasan_report_invalid_free() + * is triggered by explicit tag checks and not by the ones performed by + * the CPU. Thus, reporting invalid-free is not suppressed as well. + */ + if (unlikely(!report_enabled())) + return; - tagged_addr = (void *)addr; - untagged_addr = reset_tag(tagged_addr); + start_report(&flags, true); - 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; + __memset(&info, 0, sizeof(info)); + info.type = type; + info.access_addr = ptr; + info.access_size = 0; + info.is_write = false; info.ip = ip; - start_report(&flags); - - print_error_description(&info); - if (addr_has_shadow(untagged_addr)) - print_tags(get_tag(tagged_addr), info.first_bad_addr); - pr_err("\n"); + complete_report_info(&info); - 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(); - } + print_report(&info); - end_report(&flags); + /* + * Invalid free is considered a "write" since the allocator's metadata + * updates involves writes. + */ + end_report(&flags, ptr, true); } -bool kasan_report(unsigned long addr, size_t size, bool is_write, +/* + * kasan_report() is the only reporting function that uses + * user_access_save/restore(): kasan_report_invalid_free() cannot be called + * from a UACCESS region, and kasan_report_async() is not used on x86. + */ +bool kasan_report(const void *addr, size_t size, bool is_write, unsigned long ip) { - unsigned long flags = user_access_save(); - bool ret = false; - - if (likely(report_enabled())) { - __kasan_report(addr, size, is_write, ip); - ret = true; + bool ret = true; + unsigned long ua_flags = user_access_save(); + unsigned long irq_flags; + struct kasan_report_info info; + + if (unlikely(report_suppressed_sw()) || unlikely(!report_enabled())) { + ret = false; + goto out; } - user_access_restore(flags); + start_report(&irq_flags, true); + + __memset(&info, 0, sizeof(info)); + info.type = KASAN_REPORT_ACCESS; + info.access_addr = addr; + info.access_size = size; + info.is_write = is_write; + info.ip = ip; + + complete_report_info(&info); + + print_report(&info); + + end_report(&irq_flags, (void *)addr, is_write); + +out: + user_access_restore(ua_flags); return ret; } -#ifdef CONFIG_KASAN_INLINE +#ifdef CONFIG_KASAN_HW_TAGS +void kasan_report_async(void) +{ + unsigned long flags; + + /* + * Do not check report_suppressed_sw(), as + * kasan_disable/enable_current() critical sections do not affect + * Hardware Tag-Based KASAN. + */ + if (unlikely(!report_enabled())) + return; + + start_report(&flags, false); + pr_err("BUG: KASAN: invalid-access\n"); + pr_err("Asynchronous fault: no details available\n"); + pr_err("\n"); + dump_stack_lvl(KERN_ERR); + /* + * Conservatively set is_write=true, because no details are available. + * In this mode, kasan.fault=panic_on_write is like kasan.fault=panic. + */ + end_report(&flags, NULL, true); +} +#endif /* CONFIG_KASAN_HW_TAGS */ + +#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS) /* - * With CONFIG_KASAN_INLINE, accesses to bogus pointers (outside the high - * canonical half of the address space) cause out-of-bounds shadow memory reads - * before the actual access. For addresses in the low canonical half of the - * address space, as well as most non-canonical addresses, that out-of-bounds - * shadow memory access lands in the non-canonical part of the address space. - * Help the user figure out what the original bogus pointer was. + * With compiler-based KASAN modes, accesses to bogus pointers (outside of the + * mapped kernel address space regions) cause faults when KASAN tries to check + * the shadow memory before the actual memory access. This results in cryptic + * GPF reports, which are hard for users to interpret. This hook helps users to + * figure out what the original bogus pointer was. */ void kasan_non_canonical_hook(unsigned long addr) { unsigned long orig_addr; const char *bug_type; + /* + * All addresses that came as a result of the memory-to-shadow mapping + * (even for bogus pointers) must be >= KASAN_SHADOW_OFFSET. + */ if (addr < KASAN_SHADOW_OFFSET) return; - orig_addr = (addr - KASAN_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT; + orig_addr = (unsigned long)kasan_shadow_to_mem((void *)addr); + /* * For faults near the shadow address for NULL, we can be fairly certain * that this is a KASAN shadow memory access. - * For faults that correspond to shadow for low canonical addresses, we - * can still be pretty sure - that shadow region is a fairly narrow - * chunk of the non-canonical address space. - * But faults that look like shadow for non-canonical addresses are a - * really large chunk of the address space. In that case, we still - * print the decoded address, but make it clear that this is not - * necessarily what's actually going on. + * For faults that correspond to the shadow for low or high canonical + * addresses, we can still be pretty sure: these shadow regions are a + * fairly narrow chunk of the address space. + * But the shadow for non-canonical addresses is a really large chunk + * of the address space. For this case, we still print the decoded + * address, but make it clear that this is not necessarily what's + * actually going on. */ if (orig_addr < PAGE_SIZE) bug_type = "null-ptr-deref"; else if (orig_addr < TASK_SIZE) bug_type = "probably user-memory-access"; + else if (addr_in_shadow((void *)addr)) + bug_type = "probably wild-memory-access"; else bug_type = "maybe wild-memory-access"; pr_alert("KASAN: %s in range [0x%016lx-0x%016lx]\n", bug_type, - orig_addr, orig_addr + KASAN_SHADOW_MASK); + orig_addr, orig_addr + KASAN_GRANULE_SIZE - 1); } #endif |