cregit-Linux how code gets into the kernel

Release 4.8 mm/kasan/report.c

Directory: mm/kasan
/*
 * This file contains 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 <adech.fo@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 <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 <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 const void *find_first_bad_addr(const void *addr, size_t size) { u8 shadow_val = *(u8 *)kasan_mem_to_shadow(addr); const void *first_bad_addr = addr; while (!shadow_val && first_bad_addr < addr + size) { first_bad_addr += KASAN_SHADOW_SCALE_SIZE; shadow_val = *(u8 *)kasan_mem_to_shadow(first_bad_addr); } return first_bad_addr; }

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andrey ryabininandrey ryabinin68100.00%1100.00%
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static void print_error_description(struct kasan_access_info *info) { const char *bug_type = "unknown-crash"; u8 *shadow_addr; info->first_bad_addr = find_first_bad_addr(info->access_addr, info->access_size); shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr); /* * If shadow byte value is in [0, KASAN_SHADOW_SCALE_SIZE) we can look * at the next shadow byte to determine the type of the bad access. */ if (*shadow_addr > 0 && *shadow_addr <= KASAN_SHADOW_SCALE_SIZE - 1) shadow_addr++; switch (*shadow_addr) { case 0 ... KASAN_SHADOW_SCALE_SIZE - 1: /* * In theory it's still possible to see these shadow values * due to a data race in the kernel code. */ bug_type = "out-of-bounds"; break; case KASAN_PAGE_REDZONE: case KASAN_KMALLOC_REDZONE: bug_type = "slab-out-of-bounds"; break; case KASAN_GLOBAL_REDZONE: bug_type = "global-out-of-bounds"; break; case KASAN_STACK_LEFT: case KASAN_STACK_MID: case KASAN_STACK_RIGHT: case KASAN_STACK_PARTIAL: bug_type = "stack-out-of-bounds"; break; case KASAN_FREE_PAGE: case KASAN_KMALLOC_FREE: bug_type = "use-after-free"; break; } pr_err("BUG: KASAN: %s in %pS at addr %p\n", bug_type, (void *)info->ip, info->access_addr); pr_err("%s of size %zu by task %s/%d\n", info->is_write ? "Write" : "Read", info->access_size, current->comm, task_pid_nr(current)); }

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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; }

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aneesh kumaraneesh kumar1938.00%150.00%
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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)); }

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static DEFINE_SPINLOCK(report_lock);
static void kasan_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"); }

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static void kasan_end_report(unsigned long *flags) { pr_err("==================================================================\n"); add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); spin_unlock_irqrestore(&report_lock, *flags); kasan_enable_current(); }

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static void print_track(struct kasan_track *track) { pr_err("PID = %u\n", track->pid); if (track->stack) { struct stack_trace trace; depot_fetch_stack(track->stack, &trace); print_stack_trace(&trace, 0); } else { pr_err("(stack is not available)\n"); } }

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alexander potapenkoalexander potapenko58100.00%2100.00%
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static void kasan_object_err(struct kmem_cache *cache, void *object) { struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object); dump_stack(); pr_err("Object at %p, in cache %s size: %d\n", object, cache->name, cache->object_size); if (!(cache->flags & SLAB_KASAN)) return; pr_err("Allocated:\n"); print_track(&alloc_info->alloc_track); pr_err("Freed:\n"); print_track(&alloc_info->free_track); }

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alexander potapenkoalexander potapenko7489.16%250.00%
andrey ryabininandrey ryabinin910.84%250.00%
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void kasan_report_double_free(struct kmem_cache *cache, void *object, s8 shadow) { unsigned long flags; kasan_start_report(&flags); pr_err("BUG: Double free or freeing an invalid pointer\n"); pr_err("Unexpected shadow byte: 0x%hhX\n", shadow); kasan_object_err(cache, object); kasan_end_report(&flags); }

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static void print_address_description(struct kasan_access_info *info) { const void *addr = info->access_addr; if ((addr >= (void *)PAGE_OFFSET) && (addr < high_memory)) { struct page *page = virt_to_head_page(addr); if (PageSlab(page)) { void *object; struct kmem_cache *cache = page->slab_cache; object = nearest_obj(cache, page, (void *)info->access_addr); kasan_object_err(cache, object); return; } dump_page(page, "kasan: bad access detected"); } if (kernel_or_module_addr(addr)) { if (!init_task_stack_addr(addr)) pr_err("Address belongs to variable %pS\n", addr); } dump_stack(); }

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alexander potapenkoalexander potapenko75.34%233.33%
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static bool row_is_guilty(const void *row, const void *guilty) { return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW); }

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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; }

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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) ? ">%p: " : " %p: ", 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)) pr_err("%*c\n", shadow_pointer_offset(shadow_row, shadow), '^'); shadow_row += SHADOW_BYTES_PER_ROW; } }

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andrey ryabininandrey ryabinin16290.50%150.00%
aneesh kumaraneesh kumar179.50%150.00%
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static void kasan_report_error(struct kasan_access_info *info) { unsigned long flags; const char *bug_type; kasan_start_report(&flags); if (info->access_addr < kasan_shadow_to_mem((void *)KASAN_SHADOW_START)) { if ((unsigned long)info->access_addr < PAGE_SIZE) bug_type = "null-ptr-deref"; else if ((unsigned long)info->access_addr < TASK_SIZE) bug_type = "user-memory-access"; else bug_type = "wild-memory-access"; pr_err("BUG: KASAN: %s on address %p\n", bug_type, info->access_addr); pr_err("%s of size %zu by task %s/%d\n", info->is_write ? "Write" : "Read", info->access_size, current->comm, task_pid_nr(current)); dump_stack(); } else { print_error_description(info); print_address_description(info); print_shadow_for_address(info->first_bad_addr); } kasan_end_report(&flags); }

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andrey konovalovandrey konovalov7450.34%240.00%
andrey ryabininandrey ryabinin7248.98%240.00%
aneesh kumaraneesh kumar10.68%120.00%
Total147100.00%5100.00%


void kasan_report(unsigned long addr, size_t size, bool is_write, unsigned long ip) { struct kasan_access_info info; if (likely(!kasan_report_enabled())) return; info.access_addr = (void *)addr; info.access_size = size; info.is_write = is_write; info.ip = ip; kasan_report_error(&info); }

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aneesh kumaraneesh kumar11.49%150.00%
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#define DEFINE_ASAN_REPORT_LOAD(size) \ void __asan_report_load##size##_noabort(unsigned long addr) \ { \ kasan_report(addr, size, false, _RET_IP_); \ } \ EXPORT_SYMBOL(__asan_report_load##size##_noabort) #define DEFINE_ASAN_REPORT_STORE(size) \ void __asan_report_store##size##_noabort(unsigned long addr) \ { \ kasan_report(addr, size, true, _RET_IP_); \ } \ EXPORT_SYMBOL(__asan_report_store##size##_noabort) 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) { kasan_report(addr, size, false, _RET_IP_); }

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EXPORT_SYMBOL(__asan_report_load_n_noabort);
void __asan_report_store_n_noabort(unsigned long addr, size_t size) { kasan_report(addr, size, true, _RET_IP_); }

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EXPORT_SYMBOL(__asan_report_store_n_noabort);

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andrey ryabininandrey ryabinin108077.81%840.00%
alexander potapenkoalexander potapenko14210.23%315.00%
andrey konovalovandrey konovalov1259.01%525.00%
aneesh kumaraneesh kumar412.95%420.00%
Total1388100.00%20100.00%
Directory: mm/kasan
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