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![Andrey Konovalov](/assets/img/avatar_default.png)
This is a preparatory commit for the upcoming addition of a new hardware tag-based (MTE-based) KASAN mode. Rework print_memory_metadata() to make it agnostic with regard to the way metadata is stored. Allow providing a separate metadata_fetch_row() implementation for each KASAN mode. Hardware tag-based KASAN will provide its own implementation that doesn't use shadow memory. No functional changes for software modes. Link: https://lkml.kernel.org/r/5fb1ec0152bb1f521505017800387ec3e36ffe18.1606161801.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Reviewed-by: Marco Elver <elver@google.com> Reviewed-by: Alexander Potapenko <glider@google.com> Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Branislav Rankov <Branislav.Rankov@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Evgenii Stepanov <eugenis@google.com> Cc: Kevin Brodsky <kevin.brodsky@arm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
327 lines
8.5 KiB
C
327 lines
8.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* This file contains generic KASAN specific error reporting code.
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*
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* Copyright (c) 2014 Samsung Electronics Co., Ltd.
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* Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
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*
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* Some code borrowed from https://github.com/xairy/kasan-prototype by
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* Andrey Konovalov <andreyknvl@gmail.com>
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*/
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#include <linux/bitops.h>
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#include <linux/ftrace.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/printk.h>
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#include <linux/sched.h>
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#include <linux/sched/task_stack.h>
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#include <linux/slab.h>
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#include <linux/stackdepot.h>
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#include <linux/stacktrace.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include <linux/kasan.h>
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#include <linux/module.h>
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#include <asm/sections.h>
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#include "kasan.h"
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#include "../slab.h"
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void *find_first_bad_addr(void *addr, size_t size)
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{
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void *p = addr;
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while (p < addr + size && !(*(u8 *)kasan_mem_to_shadow(p)))
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p += KASAN_GRANULE_SIZE;
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return p;
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}
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static const char *get_shadow_bug_type(struct kasan_access_info *info)
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{
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const char *bug_type = "unknown-crash";
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u8 *shadow_addr;
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shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr);
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/*
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* If shadow byte value is in [0, KASAN_GRANULE_SIZE) we can look
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* at the next shadow byte to determine the type of the bad access.
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*/
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if (*shadow_addr > 0 && *shadow_addr <= KASAN_GRANULE_SIZE - 1)
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shadow_addr++;
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switch (*shadow_addr) {
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case 0 ... KASAN_GRANULE_SIZE - 1:
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/*
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* In theory it's still possible to see these shadow values
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* due to a data race in the kernel code.
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*/
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bug_type = "out-of-bounds";
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break;
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case KASAN_PAGE_REDZONE:
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case KASAN_KMALLOC_REDZONE:
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bug_type = "slab-out-of-bounds";
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break;
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case KASAN_GLOBAL_REDZONE:
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bug_type = "global-out-of-bounds";
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break;
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case KASAN_STACK_LEFT:
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case KASAN_STACK_MID:
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case KASAN_STACK_RIGHT:
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case KASAN_STACK_PARTIAL:
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bug_type = "stack-out-of-bounds";
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break;
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case KASAN_FREE_PAGE:
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case KASAN_KMALLOC_FREE:
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case KASAN_KMALLOC_FREETRACK:
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bug_type = "use-after-free";
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break;
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case KASAN_ALLOCA_LEFT:
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case KASAN_ALLOCA_RIGHT:
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bug_type = "alloca-out-of-bounds";
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break;
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case KASAN_VMALLOC_INVALID:
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bug_type = "vmalloc-out-of-bounds";
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break;
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}
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return bug_type;
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}
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static const char *get_wild_bug_type(struct kasan_access_info *info)
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{
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const char *bug_type = "unknown-crash";
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if ((unsigned long)info->access_addr < PAGE_SIZE)
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bug_type = "null-ptr-deref";
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else if ((unsigned long)info->access_addr < TASK_SIZE)
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bug_type = "user-memory-access";
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else
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bug_type = "wild-memory-access";
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return bug_type;
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}
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const char *get_bug_type(struct kasan_access_info *info)
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{
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/*
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* If access_size is a negative number, then it has reason to be
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* defined as out-of-bounds bug type.
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*
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* Casting negative numbers to size_t would indeed turn up as
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* a large size_t and its value will be larger than ULONG_MAX/2,
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* so that this can qualify as out-of-bounds.
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*/
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if (info->access_addr + info->access_size < info->access_addr)
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return "out-of-bounds";
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if (addr_has_metadata(info->access_addr))
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return get_shadow_bug_type(info);
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return get_wild_bug_type(info);
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}
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void metadata_fetch_row(char *buffer, void *row)
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{
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memcpy(buffer, kasan_mem_to_shadow(row), META_BYTES_PER_ROW);
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}
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#if CONFIG_KASAN_STACK
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static bool __must_check tokenize_frame_descr(const char **frame_descr,
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char *token, size_t max_tok_len,
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unsigned long *value)
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{
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const char *sep = strchr(*frame_descr, ' ');
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if (sep == NULL)
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sep = *frame_descr + strlen(*frame_descr);
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if (token != NULL) {
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const size_t tok_len = sep - *frame_descr;
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if (tok_len + 1 > max_tok_len) {
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pr_err("KASAN internal error: frame description too long: %s\n",
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*frame_descr);
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return false;
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}
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/* Copy token (+ 1 byte for '\0'). */
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strlcpy(token, *frame_descr, tok_len + 1);
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}
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/* Advance frame_descr past separator. */
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*frame_descr = sep + 1;
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if (value != NULL && kstrtoul(token, 10, value)) {
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pr_err("KASAN internal error: not a valid number: %s\n", token);
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return false;
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}
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return true;
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}
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static void print_decoded_frame_descr(const char *frame_descr)
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{
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/*
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* We need to parse the following string:
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* "n alloc_1 alloc_2 ... alloc_n"
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* where alloc_i looks like
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* "offset size len name"
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* or "offset size len name:line".
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*/
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char token[64];
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unsigned long num_objects;
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if (!tokenize_frame_descr(&frame_descr, token, sizeof(token),
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&num_objects))
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return;
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pr_err("\n");
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pr_err("this frame has %lu %s:\n", num_objects,
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num_objects == 1 ? "object" : "objects");
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while (num_objects--) {
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unsigned long offset;
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unsigned long size;
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/* access offset */
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if (!tokenize_frame_descr(&frame_descr, token, sizeof(token),
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&offset))
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return;
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/* access size */
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if (!tokenize_frame_descr(&frame_descr, token, sizeof(token),
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&size))
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return;
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/* name length (unused) */
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if (!tokenize_frame_descr(&frame_descr, NULL, 0, NULL))
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return;
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/* object name */
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if (!tokenize_frame_descr(&frame_descr, token, sizeof(token),
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NULL))
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return;
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/* Strip line number; without filename it's not very helpful. */
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strreplace(token, ':', '\0');
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/* Finally, print object information. */
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pr_err(" [%lu, %lu) '%s'", offset, offset + size, token);
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}
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}
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static bool __must_check get_address_stack_frame_info(const void *addr,
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unsigned long *offset,
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const char **frame_descr,
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const void **frame_pc)
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{
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unsigned long aligned_addr;
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unsigned long mem_ptr;
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const u8 *shadow_bottom;
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const u8 *shadow_ptr;
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const unsigned long *frame;
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BUILD_BUG_ON(IS_ENABLED(CONFIG_STACK_GROWSUP));
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/*
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* NOTE: We currently only support printing frame information for
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* accesses to the task's own stack.
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*/
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if (!object_is_on_stack(addr))
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return false;
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aligned_addr = round_down((unsigned long)addr, sizeof(long));
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mem_ptr = round_down(aligned_addr, KASAN_GRANULE_SIZE);
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shadow_ptr = kasan_mem_to_shadow((void *)aligned_addr);
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shadow_bottom = kasan_mem_to_shadow(end_of_stack(current));
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while (shadow_ptr >= shadow_bottom && *shadow_ptr != KASAN_STACK_LEFT) {
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shadow_ptr--;
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mem_ptr -= KASAN_GRANULE_SIZE;
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}
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while (shadow_ptr >= shadow_bottom && *shadow_ptr == KASAN_STACK_LEFT) {
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shadow_ptr--;
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mem_ptr -= KASAN_GRANULE_SIZE;
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}
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if (shadow_ptr < shadow_bottom)
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return false;
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frame = (const unsigned long *)(mem_ptr + KASAN_GRANULE_SIZE);
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if (frame[0] != KASAN_CURRENT_STACK_FRAME_MAGIC) {
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pr_err("KASAN internal error: frame info validation failed; invalid marker: %lu\n",
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frame[0]);
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return false;
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}
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*offset = (unsigned long)addr - (unsigned long)frame;
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*frame_descr = (const char *)frame[1];
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*frame_pc = (void *)frame[2];
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return true;
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}
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void print_address_stack_frame(const void *addr)
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{
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unsigned long offset;
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const char *frame_descr;
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const void *frame_pc;
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if (!get_address_stack_frame_info(addr, &offset, &frame_descr,
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&frame_pc))
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return;
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/*
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* get_address_stack_frame_info only returns true if the given addr is
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* on the current task's stack.
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*/
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pr_err("\n");
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pr_err("addr %px is located in stack of task %s/%d at offset %lu in frame:\n",
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addr, current->comm, task_pid_nr(current), offset);
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pr_err(" %pS\n", frame_pc);
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if (!frame_descr)
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return;
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print_decoded_frame_descr(frame_descr);
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}
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#endif /* CONFIG_KASAN_STACK */
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#define DEFINE_ASAN_REPORT_LOAD(size) \
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void __asan_report_load##size##_noabort(unsigned long addr) \
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{ \
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kasan_report(addr, size, false, _RET_IP_); \
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} \
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EXPORT_SYMBOL(__asan_report_load##size##_noabort)
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#define DEFINE_ASAN_REPORT_STORE(size) \
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void __asan_report_store##size##_noabort(unsigned long addr) \
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{ \
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kasan_report(addr, size, true, _RET_IP_); \
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} \
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EXPORT_SYMBOL(__asan_report_store##size##_noabort)
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DEFINE_ASAN_REPORT_LOAD(1);
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DEFINE_ASAN_REPORT_LOAD(2);
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DEFINE_ASAN_REPORT_LOAD(4);
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DEFINE_ASAN_REPORT_LOAD(8);
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DEFINE_ASAN_REPORT_LOAD(16);
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DEFINE_ASAN_REPORT_STORE(1);
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DEFINE_ASAN_REPORT_STORE(2);
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DEFINE_ASAN_REPORT_STORE(4);
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DEFINE_ASAN_REPORT_STORE(8);
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DEFINE_ASAN_REPORT_STORE(16);
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void __asan_report_load_n_noabort(unsigned long addr, size_t size)
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{
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kasan_report(addr, size, false, _RET_IP_);
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}
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EXPORT_SYMBOL(__asan_report_load_n_noabort);
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void __asan_report_store_n_noabort(unsigned long addr, size_t size)
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{
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kasan_report(addr, size, true, _RET_IP_);
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}
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EXPORT_SYMBOL(__asan_report_store_n_noabort);
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