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8cceeff48f
Patch series "fix the missing underflow in memory operation function", v4. The patchset helps to produce a KASAN report when size is negative in memory operation functions. It is helpful for programmer to solve an undefined behavior issue. Patch 1 based on Dmitry's review and suggestion, patch 2 is a test in order to verify the patch 1. [1]https://bugzilla.kernel.org/show_bug.cgi?id=199341 [2]https://lore.kernel.org/linux-arm-kernel/20190927034338.15813-1-walter-zh.wu@mediatek.com/ This patch (of 2): KASAN missed detecting size is a negative number in memset(), memcpy(), and memmove(), it will cause out-of-bounds bug. So needs to be detected by KASAN. If size is a negative number, then it has a reason to be defined as out-of-bounds bug type. Casting negative numbers to size_t would indeed turn up as a large size_t and its value will be larger than ULONG_MAX/2, so that this can qualify as out-of-bounds. KASAN report is shown below: BUG: KASAN: out-of-bounds in kmalloc_memmove_invalid_size+0x70/0xa0 Read of size 18446744073709551608 at addr ffffff8069660904 by task cat/72 CPU: 2 PID: 72 Comm: cat Not tainted 5.4.0-rc1-next-20191004ajb-00001-gdb8af2f372b2-dirty #1 Hardware name: linux,dummy-virt (DT) Call trace: dump_backtrace+0x0/0x288 show_stack+0x14/0x20 dump_stack+0x10c/0x164 print_address_description.isra.9+0x68/0x378 __kasan_report+0x164/0x1a0 kasan_report+0xc/0x18 check_memory_region+0x174/0x1d0 memmove+0x34/0x88 kmalloc_memmove_invalid_size+0x70/0xa0 [1] https://bugzilla.kernel.org/show_bug.cgi?id=199341 [cai@lca.pw: fix -Wdeclaration-after-statement warn] Link: http://lkml.kernel.org/r/1583509030-27939-1-git-send-email-cai@lca.pw [peterz@infradead.org: fix objtool warning] Link: http://lkml.kernel.org/r/20200305095436.GV2596@hirez.programming.kicks-ass.net Reported-by: kernel test robot <lkp@intel.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Suggested-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Walter Wu <walter-zh.wu@mediatek.com> Signed-off-by: Qian Cai <cai@lca.pw> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Alexander Potapenko <glider@google.com> Link: http://lkml.kernel.org/r/20191112065302.7015-1-walter-zh.wu@mediatek.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
165 lines
4.5 KiB
C
165 lines
4.5 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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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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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/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_SHADOW_SCALE_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_SHADOW_SCALE_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_SHADOW_SCALE_SIZE - 1)
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shadow_addr++;
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switch (*shadow_addr) {
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case 0 ... KASAN_SHADOW_SCALE_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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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_shadow(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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#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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