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-rw-r--r--mm/kasan/Makefile2
-rw-r--r--mm/kasan/kasan.c41
-rw-r--r--mm/kasan/kasan.h5
-rw-r--r--mm/kasan/kasan_init.c152
-rw-r--r--mm/kasan/report.c115
5 files changed, 253 insertions, 62 deletions
diff --git a/mm/kasan/Makefile b/mm/kasan/Makefile
index bd837b8c2f41..64710148941e 100644
--- a/mm/kasan/Makefile
+++ b/mm/kasan/Makefile
@@ -5,4 +5,4 @@ CFLAGS_REMOVE_kasan.o = -pg
# see: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63533
CFLAGS_kasan.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector)
-obj-y := kasan.o report.o
+obj-y := kasan.o report.o kasan_init.o
diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index 6c513a63ea84..d41b21bce6a0 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -2,9 +2,9 @@
* This file contains shadow memory manipulation code.
*
* Copyright (c) 2014 Samsung Electronics Co., Ltd.
- * Author: Andrey Ryabinin <a.ryabinin@samsung.com>
+ * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
*
- * Some of code borrowed from https://github.com/xairy/linux by
+ * 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
@@ -86,6 +86,11 @@ static __always_inline bool memory_is_poisoned_2(unsigned long addr)
if (memory_is_poisoned_1(addr + 1))
return true;
+ /*
+ * If single shadow byte covers 2-byte access, we don't
+ * need to do anything more. Otherwise, test the first
+ * shadow byte.
+ */
if (likely(((addr + 1) & KASAN_SHADOW_MASK) != 0))
return false;
@@ -103,6 +108,11 @@ static __always_inline bool memory_is_poisoned_4(unsigned long addr)
if (memory_is_poisoned_1(addr + 3))
return true;
+ /*
+ * If single shadow byte covers 4-byte access, we don't
+ * need to do anything more. Otherwise, test the first
+ * shadow byte.
+ */
if (likely(((addr + 3) & KASAN_SHADOW_MASK) >= 3))
return false;
@@ -120,7 +130,12 @@ static __always_inline bool memory_is_poisoned_8(unsigned long addr)
if (memory_is_poisoned_1(addr + 7))
return true;
- if (likely(((addr + 7) & KASAN_SHADOW_MASK) >= 7))
+ /*
+ * If single shadow byte covers 8-byte access, we don't
+ * need to do anything more. Otherwise, test the first
+ * shadow byte.
+ */
+ if (likely(IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE)))
return false;
return unlikely(*(u8 *)shadow_addr);
@@ -135,12 +150,16 @@ static __always_inline bool memory_is_poisoned_16(unsigned long addr)
if (unlikely(*shadow_addr)) {
u16 shadow_first_bytes = *(u16 *)shadow_addr;
- s8 last_byte = (addr + 15) & KASAN_SHADOW_MASK;
if (unlikely(shadow_first_bytes))
return true;
- if (likely(!last_byte))
+ /*
+ * If two shadow bytes covers 16-byte access, we don't
+ * need to do anything more. Otherwise, test the last
+ * shadow byte.
+ */
+ if (likely(IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE)))
return false;
return memory_is_poisoned_1(addr + 15);
@@ -204,7 +223,7 @@ static __always_inline bool memory_is_poisoned_n(unsigned long addr,
s8 *last_shadow = (s8 *)kasan_mem_to_shadow((void *)last_byte);
if (unlikely(ret != (unsigned long)last_shadow ||
- ((last_byte & KASAN_SHADOW_MASK) >= *last_shadow)))
+ ((long)(last_byte & KASAN_SHADOW_MASK) >= *last_shadow)))
return true;
}
return false;
@@ -236,18 +255,12 @@ static __always_inline bool memory_is_poisoned(unsigned long addr, size_t size)
static __always_inline void check_memory_region(unsigned long addr,
size_t size, bool write)
{
- struct kasan_access_info info;
-
if (unlikely(size == 0))
return;
if (unlikely((void *)addr <
kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
- info.access_addr = (void *)addr;
- info.access_size = size;
- info.is_write = write;
- info.ip = _RET_IP_;
- kasan_report_user_access(&info);
+ kasan_report(addr, size, write, _RET_IP_);
return;
}
@@ -525,7 +538,7 @@ static int kasan_mem_notifier(struct notifier_block *nb,
static int __init kasan_memhotplug_init(void)
{
- pr_err("WARNING: KASan doesn't support memory hot-add\n");
+ pr_err("WARNING: KASAN doesn't support memory hot-add\n");
pr_err("Memory hot-add will be disabled\n");
hotplug_memory_notifier(kasan_mem_notifier, 0);
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index c242adf6bc85..4f6c62e5c21e 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -54,16 +54,13 @@ struct kasan_global {
#endif
};
-void kasan_report_error(struct kasan_access_info *info);
-void kasan_report_user_access(struct kasan_access_info *info);
-
static inline const void *kasan_shadow_to_mem(const void *shadow_addr)
{
return (void *)(((unsigned long)shadow_addr - KASAN_SHADOW_OFFSET)
<< KASAN_SHADOW_SCALE_SHIFT);
}
-static inline bool kasan_enabled(void)
+static inline bool kasan_report_enabled(void)
{
return !current->kasan_depth;
}
diff --git a/mm/kasan/kasan_init.c b/mm/kasan/kasan_init.c
new file mode 100644
index 000000000000..3f9a41cf0ac6
--- /dev/null
+++ b/mm/kasan/kasan_init.c
@@ -0,0 +1,152 @@
+/*
+ * This file contains some kasan initialization code.
+ *
+ * Copyright (c) 2015 Samsung Electronics Co., Ltd.
+ * Author: Andrey Ryabinin <ryabinin.a.a@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/bootmem.h>
+#include <linux/init.h>
+#include <linux/kasan.h>
+#include <linux/kernel.h>
+#include <linux/memblock.h>
+#include <linux/pfn.h>
+
+#include <asm/page.h>
+#include <asm/pgalloc.h>
+
+/*
+ * This page serves two purposes:
+ * - It used as early shadow memory. The entire shadow region populated
+ * with this page, before we will be able to setup normal shadow memory.
+ * - Latter it reused it as zero shadow to cover large ranges of memory
+ * that allowed to access, but not handled by kasan (vmalloc/vmemmap ...).
+ */
+unsigned char kasan_zero_page[PAGE_SIZE] __page_aligned_bss;
+
+#if CONFIG_PGTABLE_LEVELS > 3
+pud_t kasan_zero_pud[PTRS_PER_PUD] __page_aligned_bss;
+#endif
+#if CONFIG_PGTABLE_LEVELS > 2
+pmd_t kasan_zero_pmd[PTRS_PER_PMD] __page_aligned_bss;
+#endif
+pte_t kasan_zero_pte[PTRS_PER_PTE] __page_aligned_bss;
+
+static __init void *early_alloc(size_t size, int node)
+{
+ return memblock_virt_alloc_try_nid(size, size, __pa(MAX_DMA_ADDRESS),
+ BOOTMEM_ALLOC_ACCESSIBLE, node);
+}
+
+static void __init zero_pte_populate(pmd_t *pmd, unsigned long addr,
+ unsigned long end)
+{
+ pte_t *pte = pte_offset_kernel(pmd, addr);
+ pte_t zero_pte;
+
+ zero_pte = pfn_pte(PFN_DOWN(__pa(kasan_zero_page)), PAGE_KERNEL);
+ zero_pte = pte_wrprotect(zero_pte);
+
+ while (addr + PAGE_SIZE <= end) {
+ set_pte_at(&init_mm, addr, pte, zero_pte);
+ addr += PAGE_SIZE;
+ pte = pte_offset_kernel(pmd, addr);
+ }
+}
+
+static void __init zero_pmd_populate(pud_t *pud, unsigned long addr,
+ unsigned long end)
+{
+ pmd_t *pmd = pmd_offset(pud, addr);
+ unsigned long next;
+
+ do {
+ next = pmd_addr_end(addr, end);
+
+ if (IS_ALIGNED(addr, PMD_SIZE) && end - addr >= PMD_SIZE) {
+ pmd_populate_kernel(&init_mm, pmd, kasan_zero_pte);
+ continue;
+ }
+
+ if (pmd_none(*pmd)) {
+ pmd_populate_kernel(&init_mm, pmd,
+ early_alloc(PAGE_SIZE, NUMA_NO_NODE));
+ }
+ zero_pte_populate(pmd, addr, next);
+ } while (pmd++, addr = next, addr != end);
+}
+
+static void __init zero_pud_populate(pgd_t *pgd, unsigned long addr,
+ unsigned long end)
+{
+ pud_t *pud = pud_offset(pgd, addr);
+ unsigned long next;
+
+ do {
+ next = pud_addr_end(addr, end);
+ if (IS_ALIGNED(addr, PUD_SIZE) && end - addr >= PUD_SIZE) {
+ pmd_t *pmd;
+
+ pud_populate(&init_mm, pud, kasan_zero_pmd);
+ pmd = pmd_offset(pud, addr);
+ pmd_populate_kernel(&init_mm, pmd, kasan_zero_pte);
+ continue;
+ }
+
+ if (pud_none(*pud)) {
+ pud_populate(&init_mm, pud,
+ early_alloc(PAGE_SIZE, NUMA_NO_NODE));
+ }
+ zero_pmd_populate(pud, addr, next);
+ } while (pud++, addr = next, addr != end);
+}
+
+/**
+ * kasan_populate_zero_shadow - populate shadow memory region with
+ * kasan_zero_page
+ * @shadow_start - start of the memory range to populate
+ * @shadow_end - end of the memory range to populate
+ */
+void __init kasan_populate_zero_shadow(const void *shadow_start,
+ const void *shadow_end)
+{
+ unsigned long addr = (unsigned long)shadow_start;
+ unsigned long end = (unsigned long)shadow_end;
+ pgd_t *pgd = pgd_offset_k(addr);
+ unsigned long next;
+
+ do {
+ next = pgd_addr_end(addr, end);
+
+ if (IS_ALIGNED(addr, PGDIR_SIZE) && end - addr >= PGDIR_SIZE) {
+ pud_t *pud;
+ pmd_t *pmd;
+
+ /*
+ * kasan_zero_pud should be populated with pmds
+ * at this moment.
+ * [pud,pmd]_populate*() below needed only for
+ * 3,2 - level page tables where we don't have
+ * puds,pmds, so pgd_populate(), pud_populate()
+ * is noops.
+ */
+ pgd_populate(&init_mm, pgd, kasan_zero_pud);
+ pud = pud_offset(pgd, addr);
+ pud_populate(&init_mm, pud, kasan_zero_pmd);
+ pmd = pmd_offset(pud, addr);
+ pmd_populate_kernel(&init_mm, pmd, kasan_zero_pte);
+ continue;
+ }
+
+ if (pgd_none(*pgd)) {
+ pgd_populate(&init_mm, pgd,
+ early_alloc(PAGE_SIZE, NUMA_NO_NODE));
+ }
+ zero_pud_populate(pgd, addr, next);
+ } while (pgd++, addr = next, addr != end);
+}
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index 680ceedf810a..12f222d0224b 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -2,9 +2,9 @@
* This file contains error reporting code.
*
* Copyright (c) 2014 Samsung Electronics Co., Ltd.
- * Author: Andrey Ryabinin <a.ryabinin@samsung.com>
+ * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
*
- * Some of code borrowed from https://github.com/xairy/linux by
+ * 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
@@ -22,6 +22,7 @@
#include <linux/string.h>
#include <linux/types.h>
#include <linux/kasan.h>
+#include <linux/module.h>
#include <asm/sections.h>
@@ -48,34 +49,49 @@ static const void *find_first_bad_addr(const void *addr, size_t size)
static void print_error_description(struct kasan_access_info *info)
{
- const char *bug_type = "unknown crash";
- u8 shadow_val;
+ const char *bug_type = "unknown-crash";
+ u8 *shadow_addr;
info->first_bad_addr = find_first_bad_addr(info->access_addr,
info->access_size);
- shadow_val = *(u8 *)kasan_mem_to_shadow(info->first_bad_addr);
+ shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr);
- switch (shadow_val) {
- case KASAN_FREE_PAGE:
- case KASAN_KMALLOC_FREE:
- bug_type = "use after free";
+ /*
+ * 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:
- case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
- bug_type = "out of bounds access";
+ 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 = "out of bounds on stack";
+ 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",
+ 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",
@@ -85,9 +101,11 @@ static void print_error_description(struct kasan_access_info *info)
static inline bool kernel_or_module_addr(const void *addr)
{
- return (addr >= (void *)_stext && addr < (void *)_end)
- || (addr >= (void *)MODULES_VADDR
- && addr < (void *)MODULES_END);
+ 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)
@@ -161,15 +179,19 @@ static void print_shadow_for_address(const void *addr)
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);
-
- kasan_disable_current();
+ /*
+ * 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_row, SHADOW_BYTES_PER_ROW, 0);
- kasan_enable_current();
+ shadow_buf, SHADOW_BYTES_PER_ROW, 0);
if (row_is_guilty(shadow_row, shadow))
pr_err("%*c\n",
@@ -182,37 +204,43 @@ static void print_shadow_for_address(const void *addr)
static DEFINE_SPINLOCK(report_lock);
-void kasan_report_error(struct kasan_access_info *info)
-{
- unsigned long flags;
-
- spin_lock_irqsave(&report_lock, flags);
- pr_err("================================="
- "=================================\n");
- print_error_description(info);
- print_address_description(info);
- print_shadow_for_address(info->first_bad_addr);
- pr_err("================================="
- "=================================\n");
- spin_unlock_irqrestore(&report_lock, flags);
-}
-
-void kasan_report_user_access(struct kasan_access_info *info)
+static void kasan_report_error(struct kasan_access_info *info)
{
unsigned long flags;
+ const char *bug_type;
+ /*
+ * Make sure we don't end up in loop.
+ */
+ kasan_disable_current();
spin_lock_irqsave(&report_lock, flags);
pr_err("================================="
"=================================\n");
- pr_err("BUG: KASan: user-memory-access on address %p\n",
- 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();
+ 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);
+ }
pr_err("================================="
"=================================\n");
+ add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
spin_unlock_irqrestore(&report_lock, flags);
+ kasan_enable_current();
}
void kasan_report(unsigned long addr, size_t size,
@@ -220,13 +248,14 @@ void kasan_report(unsigned long addr, size_t size,
{
struct kasan_access_info info;
- if (likely(!kasan_enabled()))
+ 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);
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-26 13:37:32 +0100