123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469470471472473474475476477478479480481482483 |
- // SPDX-License-Identifier: GPL-2.0
- /*
- * 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>
- */
- #include <linux/bitops.h>
- #include <linux/ftrace.h>
- #include <linux/init.h>
- #include <linux/kernel.h>
- #include <linux/mm.h>
- #include <linux/printk.h>
- #include <linux/sched.h>
- #include <linux/slab.h>
- #include <linux/stackdepot.h>
- #include <linux/stacktrace.h>
- #include <linux/string.h>
- #include <linux/types.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 <kunit/test.h>
- #include "kasan.h"
- #include "../slab.h"
- 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 int __init kasan_set_multi_shot(char *str)
- {
- set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
- return 1;
- }
- __setup("kasan_multi_shot", kasan_set_multi_shot);
- static void print_error_description(struct kasan_access_info *info)
- {
- pr_err("BUG: KASAN: %s in %pS\n",
- kasan_get_bug_type(info), (void *)info->ip);
- 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 DEFINE_SPINLOCK(report_lock);
- static void start_report(unsigned long *flags)
- {
- /*
- * Make sure we don't end up in loop.
- */
- kasan_disable_current();
- spin_lock_irqsave(&report_lock, *flags);
- pr_err("==================================================================\n");
- }
- static void end_report(unsigned long *flags, unsigned long addr)
- {
- if (!kasan_async_mode_enabled())
- trace_error_report_end(ERROR_DETECTOR_KASAN, addr);
- pr_err("==================================================================\n");
- add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
- spin_unlock_irqrestore(&report_lock, *flags);
- if (panic_on_warn && !test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags)) {
- /*
- * 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
- if (kasan_flag_panic)
- panic("kasan.fault=panic set ...\n");
- #endif
- kasan_enable_current();
- }
- static void print_stack(depot_stack_handle_t stack)
- {
- unsigned long *entries;
- unsigned int nr_entries;
- nr_entries = stack_depot_fetch(stack, &entries);
- stack_trace_print(entries, nr_entries, 0);
- }
- static void print_track(struct kasan_track *track, const char *prefix)
- {
- pr_err("%s by task %u:\n", prefix, track->pid);
- if (track->stack) {
- print_stack(track->stack);
- } else {
- pr_err("(stack is not available)\n");
- }
- }
- struct page *kasan_addr_to_page(const void *addr)
- {
- if ((addr >= (void *)PAGE_OFFSET) &&
- (addr < high_memory))
- return virt_to_head_page(addr);
- return NULL;
- }
- static void describe_object_addr(struct kmem_cache *cache, void *object,
- const void *addr)
- {
- unsigned long access_addr = (unsigned long)addr;
- unsigned long object_addr = (unsigned long)object;
- const char *rel_type;
- int rel_bytes;
- 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);
- if (!addr)
- return;
- 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;
- }
- 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));
- }
- static void describe_object_stacks(struct kmem_cache *cache, void *object,
- const void *addr, u8 tag)
- {
- struct kasan_alloc_meta *alloc_meta;
- struct kasan_track *free_track;
- alloc_meta = kasan_get_alloc_meta(cache, object);
- if (alloc_meta) {
- print_track(&alloc_meta->alloc_track, "Allocated");
- pr_err("\n");
- }
- free_track = kasan_get_free_track(cache, object, tag);
- if (free_track) {
- print_track(free_track, "Freed");
- pr_err("\n");
- }
- #ifdef CONFIG_KASAN_GENERIC
- if (!alloc_meta)
- return;
- if (alloc_meta->aux_stack[0]) {
- pr_err("Last potentially related work creation:\n");
- print_stack(alloc_meta->aux_stack[0]);
- pr_err("\n");
- }
- if (alloc_meta->aux_stack[1]) {
- pr_err("Second to last potentially related work creation:\n");
- print_stack(alloc_meta->aux_stack[1]);
- pr_err("\n");
- }
- #endif
- }
- static void describe_object(struct kmem_cache *cache, void *object,
- const void *addr, u8 tag)
- {
- if (kasan_stack_collection_enabled())
- describe_object_stacks(cache, object, addr, tag);
- describe_object_addr(cache, object, addr);
- }
- 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;
- }
- 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)
- {
- struct page *page = kasan_addr_to_page(addr);
- 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 (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);
- }
- if (page) {
- pr_err("The buggy address belongs to the page:\n");
- dump_page(page, "kasan: bad access detected");
- }
- kasan_print_address_stack_frame(addr);
- }
- static bool meta_row_is_guilty(const void *row, const void *addr)
- {
- return (row <= addr) && (addr < row + META_MEM_BYTES_PER_ROW);
- }
- static int meta_pointer_offset(const void *row, const void *addr)
- {
- /*
- * 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 +
- (addr - row) / KASAN_GRANULE_SIZE * 3 + 1;
- }
- static void print_memory_metadata(const void *addr)
- {
- int i;
- void *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 = -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: ", row);
- /*
- * We should not pass a shadow pointer to generic
- * function, because generic functions may try to
- * access kasan mapping for the passed address.
- */
- kasan_metadata_fetch_row(&metadata[0], row);
- print_hex_dump(KERN_ERR, buffer,
- DUMP_PREFIX_NONE, META_BYTES_PER_ROW, 1,
- metadata, META_BYTES_PER_ROW, 0);
- if (meta_row_is_guilty(row, addr))
- pr_err("%*c\n", meta_pointer_offset(row, addr), '^');
- row += META_MEM_BYTES_PER_ROW;
- }
- }
- static bool report_enabled(void)
- {
- #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
- if (current->kasan_depth)
- return false;
- #endif
- if (test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags))
- return true;
- return !test_and_set_bit(KASAN_BIT_REPORTED, &kasan_flags);
- }
- #if IS_ENABLED(CONFIG_KUNIT)
- static void kasan_update_kunit_status(struct kunit *cur_test)
- {
- struct kunit_resource *resource;
- struct kunit_kasan_expectation *kasan_data;
- resource = kunit_find_named_resource(cur_test, "kasan_data");
- if (!resource) {
- kunit_set_failure(cur_test);
- return;
- }
- kasan_data = (struct kunit_kasan_expectation *)resource->data;
- WRITE_ONCE(kasan_data->report_found, true);
- kunit_put_resource(resource);
- }
- #endif /* IS_ENABLED(CONFIG_KUNIT) */
- void kasan_report_invalid_free(void *object, unsigned long ip)
- {
- unsigned long flags;
- u8 tag = get_tag(object);
- object = kasan_reset_tag(object);
- #if IS_ENABLED(CONFIG_KUNIT)
- if (current->kunit_test)
- kasan_update_kunit_status(current->kunit_test);
- #endif /* IS_ENABLED(CONFIG_KUNIT) */
- start_report(&flags);
- pr_err("BUG: KASAN: double-free or invalid-free in %pS\n", (void *)ip);
- kasan_print_tags(tag, object);
- pr_err("\n");
- print_address_description(object, tag);
- pr_err("\n");
- print_memory_metadata(object);
- end_report(&flags, (unsigned long)object);
- }
- #ifdef CONFIG_KASAN_HW_TAGS
- void kasan_report_async(void)
- {
- unsigned long flags;
- #if IS_ENABLED(CONFIG_KUNIT)
- if (current->kunit_test)
- kasan_update_kunit_status(current->kunit_test);
- #endif /* IS_ENABLED(CONFIG_KUNIT) */
- start_report(&flags);
- pr_err("BUG: KASAN: invalid-access\n");
- pr_err("Asynchronous mode enabled: no access details available\n");
- pr_err("\n");
- dump_stack_lvl(KERN_ERR);
- end_report(&flags, 0);
- }
- #endif /* CONFIG_KASAN_HW_TAGS */
- 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;
- #if IS_ENABLED(CONFIG_KUNIT)
- if (current->kunit_test)
- kasan_update_kunit_status(current->kunit_test);
- #endif /* IS_ENABLED(CONFIG_KUNIT) */
- disable_trace_on_warning();
- tagged_addr = (void *)addr;
- untagged_addr = kasan_reset_tag(tagged_addr);
- info.access_addr = tagged_addr;
- if (addr_has_metadata(untagged_addr))
- info.first_bad_addr =
- kasan_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);
- if (addr_has_metadata(untagged_addr))
- kasan_print_tags(get_tag(tagged_addr), info.first_bad_addr);
- pr_err("\n");
- if (addr_has_metadata(untagged_addr)) {
- print_address_description(untagged_addr, get_tag(tagged_addr));
- pr_err("\n");
- print_memory_metadata(info.first_bad_addr);
- } else {
- dump_stack_lvl(KERN_ERR);
- }
- end_report(&flags, addr);
- }
- bool kasan_report(unsigned long 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;
- }
- user_access_restore(flags);
- return ret;
- }
- #ifdef CONFIG_KASAN_INLINE
- /*
- * 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.
- */
- void kasan_non_canonical_hook(unsigned long addr)
- {
- unsigned long orig_addr;
- const char *bug_type;
- if (addr < KASAN_SHADOW_OFFSET)
- return;
- orig_addr = (addr - KASAN_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT;
- /*
- * 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.
- */
- if (orig_addr < PAGE_SIZE)
- bug_type = "null-ptr-deref";
- else if (orig_addr < TASK_SIZE)
- bug_type = "probably user-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_GRANULE_SIZE - 1);
- }
- #endif
|