linux/lib/ubsan.c
Julien Grall ce5c31db36 lib/ubsan: don't serialize UBSAN report
At the moment, UBSAN report will be serialized using a spin_lock().  On
RT-systems, spinlocks are turned to rt_spin_lock and may sleep.  This
will result to the following splat if the undefined behavior is in a
context that can sleep:

  BUG: sleeping function called from invalid context at /src/linux/kernel/locking/rtmutex.c:968
  in_atomic(): 1, irqs_disabled(): 128, pid: 3447, name: make
  1 lock held by make/3447:
   #0: 000000009a966332 (&mm->mmap_sem){++++}, at: do_page_fault+0x140/0x4f8
  irq event stamp: 6284
  hardirqs last  enabled at (6283): [<ffff000011326520>] _raw_spin_unlock_irqrestore+0x90/0xa0
  hardirqs last disabled at (6284): [<ffff0000113262b0>] _raw_spin_lock_irqsave+0x30/0x78
  softirqs last  enabled at (2430): [<ffff000010088ef8>] fpsimd_restore_current_state+0x60/0xe8
  softirqs last disabled at (2427): [<ffff000010088ec0>] fpsimd_restore_current_state+0x28/0xe8
  Preemption disabled at:
  [<ffff000011324a4c>] rt_mutex_futex_unlock+0x4c/0xb0
  CPU: 3 PID: 3447 Comm: make Tainted: G        W         5.2.14-rt7-01890-ge6e057589653 #911
  Call trace:
    dump_backtrace+0x0/0x148
    show_stack+0x14/0x20
    dump_stack+0xbc/0x104
    ___might_sleep+0x154/0x210
    rt_spin_lock+0x68/0xa0
    ubsan_prologue+0x30/0x68
    handle_overflow+0x64/0xe0
    __ubsan_handle_add_overflow+0x10/0x18
    __lock_acquire+0x1c28/0x2a28
    lock_acquire+0xf0/0x370
    _raw_spin_lock_irqsave+0x58/0x78
    rt_mutex_futex_unlock+0x4c/0xb0
    rt_spin_unlock+0x28/0x70
    get_page_from_freelist+0x428/0x2b60
    __alloc_pages_nodemask+0x174/0x1708
    alloc_pages_vma+0x1ac/0x238
    __handle_mm_fault+0x4ac/0x10b0
    handle_mm_fault+0x1d8/0x3b0
    do_page_fault+0x1c8/0x4f8
    do_translation_fault+0xb8/0xe0
    do_mem_abort+0x3c/0x98
    el0_da+0x20/0x24

The spin_lock() will protect against multiple CPUs to output a report
together, I guess to prevent them from being interleaved.  However, they
can still interleave with other messages (and even splat from
__might_sleep).

So the lock usefulness seems pretty limited.  Rather than trying to
accomodate RT-system by switching to a raw_spin_lock(), the lock is now
completely dropped.

Link: http://lkml.kernel.org/r/20190920100835.14999-1-julien.grall@arm.com
Signed-off-by: Julien Grall <julien.grall@arm.com>
Reported-by: Andre Przywara <andre.przywara@arm.com>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-12-04 19:44:14 -08:00

424 lines
10 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* UBSAN error reporting functions
*
* Copyright (c) 2014 Samsung Electronics Co., Ltd.
* Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
*/
#include <linux/bitops.h>
#include <linux/bug.h>
#include <linux/ctype.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/uaccess.h>
#include "ubsan.h"
const char *type_check_kinds[] = {
"load of",
"store to",
"reference binding to",
"member access within",
"member call on",
"constructor call on",
"downcast of",
"downcast of"
};
#define REPORTED_BIT 31
#if (BITS_PER_LONG == 64) && defined(__BIG_ENDIAN)
#define COLUMN_MASK (~(1U << REPORTED_BIT))
#define LINE_MASK (~0U)
#else
#define COLUMN_MASK (~0U)
#define LINE_MASK (~(1U << REPORTED_BIT))
#endif
#define VALUE_LENGTH 40
static bool was_reported(struct source_location *location)
{
return test_and_set_bit(REPORTED_BIT, &location->reported);
}
static void print_source_location(const char *prefix,
struct source_location *loc)
{
pr_err("%s %s:%d:%d\n", prefix, loc->file_name,
loc->line & LINE_MASK, loc->column & COLUMN_MASK);
}
static bool suppress_report(struct source_location *loc)
{
return current->in_ubsan || was_reported(loc);
}
static bool type_is_int(struct type_descriptor *type)
{
return type->type_kind == type_kind_int;
}
static bool type_is_signed(struct type_descriptor *type)
{
WARN_ON(!type_is_int(type));
return type->type_info & 1;
}
static unsigned type_bit_width(struct type_descriptor *type)
{
return 1 << (type->type_info >> 1);
}
static bool is_inline_int(struct type_descriptor *type)
{
unsigned inline_bits = sizeof(unsigned long)*8;
unsigned bits = type_bit_width(type);
WARN_ON(!type_is_int(type));
return bits <= inline_bits;
}
static s_max get_signed_val(struct type_descriptor *type, void *val)
{
if (is_inline_int(type)) {
unsigned extra_bits = sizeof(s_max)*8 - type_bit_width(type);
unsigned long ulong_val = (unsigned long)val;
return ((s_max)ulong_val) << extra_bits >> extra_bits;
}
if (type_bit_width(type) == 64)
return *(s64 *)val;
return *(s_max *)val;
}
static bool val_is_negative(struct type_descriptor *type, void *val)
{
return type_is_signed(type) && get_signed_val(type, val) < 0;
}
static u_max get_unsigned_val(struct type_descriptor *type, void *val)
{
if (is_inline_int(type))
return (unsigned long)val;
if (type_bit_width(type) == 64)
return *(u64 *)val;
return *(u_max *)val;
}
static void val_to_string(char *str, size_t size, struct type_descriptor *type,
void *value)
{
if (type_is_int(type)) {
if (type_bit_width(type) == 128) {
#if defined(CONFIG_ARCH_SUPPORTS_INT128)
u_max val = get_unsigned_val(type, value);
scnprintf(str, size, "0x%08x%08x%08x%08x",
(u32)(val >> 96),
(u32)(val >> 64),
(u32)(val >> 32),
(u32)(val));
#else
WARN_ON(1);
#endif
} else if (type_is_signed(type)) {
scnprintf(str, size, "%lld",
(s64)get_signed_val(type, value));
} else {
scnprintf(str, size, "%llu",
(u64)get_unsigned_val(type, value));
}
}
}
static void ubsan_prologue(struct source_location *location)
{
current->in_ubsan++;
pr_err("========================================"
"========================================\n");
print_source_location("UBSAN: Undefined behaviour in", location);
}
static void ubsan_epilogue(void)
{
dump_stack();
pr_err("========================================"
"========================================\n");
current->in_ubsan--;
}
static void handle_overflow(struct overflow_data *data, void *lhs,
void *rhs, char op)
{
struct type_descriptor *type = data->type;
char lhs_val_str[VALUE_LENGTH];
char rhs_val_str[VALUE_LENGTH];
if (suppress_report(&data->location))
return;
ubsan_prologue(&data->location);
val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs);
val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs);
pr_err("%s integer overflow:\n",
type_is_signed(type) ? "signed" : "unsigned");
pr_err("%s %c %s cannot be represented in type %s\n",
lhs_val_str,
op,
rhs_val_str,
type->type_name);
ubsan_epilogue();
}
void __ubsan_handle_add_overflow(struct overflow_data *data,
void *lhs, void *rhs)
{
handle_overflow(data, lhs, rhs, '+');
}
EXPORT_SYMBOL(__ubsan_handle_add_overflow);
void __ubsan_handle_sub_overflow(struct overflow_data *data,
void *lhs, void *rhs)
{
handle_overflow(data, lhs, rhs, '-');
}
EXPORT_SYMBOL(__ubsan_handle_sub_overflow);
void __ubsan_handle_mul_overflow(struct overflow_data *data,
void *lhs, void *rhs)
{
handle_overflow(data, lhs, rhs, '*');
}
EXPORT_SYMBOL(__ubsan_handle_mul_overflow);
void __ubsan_handle_negate_overflow(struct overflow_data *data,
void *old_val)
{
char old_val_str[VALUE_LENGTH];
if (suppress_report(&data->location))
return;
ubsan_prologue(&data->location);
val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val);
pr_err("negation of %s cannot be represented in type %s:\n",
old_val_str, data->type->type_name);
ubsan_epilogue();
}
EXPORT_SYMBOL(__ubsan_handle_negate_overflow);
void __ubsan_handle_divrem_overflow(struct overflow_data *data,
void *lhs, void *rhs)
{
char rhs_val_str[VALUE_LENGTH];
if (suppress_report(&data->location))
return;
ubsan_prologue(&data->location);
val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs);
if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1)
pr_err("division of %s by -1 cannot be represented in type %s\n",
rhs_val_str, data->type->type_name);
else
pr_err("division by zero\n");
ubsan_epilogue();
}
EXPORT_SYMBOL(__ubsan_handle_divrem_overflow);
static void handle_null_ptr_deref(struct type_mismatch_data_common *data)
{
if (suppress_report(data->location))
return;
ubsan_prologue(data->location);
pr_err("%s null pointer of type %s\n",
type_check_kinds[data->type_check_kind],
data->type->type_name);
ubsan_epilogue();
}
static void handle_misaligned_access(struct type_mismatch_data_common *data,
unsigned long ptr)
{
if (suppress_report(data->location))
return;
ubsan_prologue(data->location);
pr_err("%s misaligned address %p for type %s\n",
type_check_kinds[data->type_check_kind],
(void *)ptr, data->type->type_name);
pr_err("which requires %ld byte alignment\n", data->alignment);
ubsan_epilogue();
}
static void handle_object_size_mismatch(struct type_mismatch_data_common *data,
unsigned long ptr)
{
if (suppress_report(data->location))
return;
ubsan_prologue(data->location);
pr_err("%s address %p with insufficient space\n",
type_check_kinds[data->type_check_kind],
(void *) ptr);
pr_err("for an object of type %s\n", data->type->type_name);
ubsan_epilogue();
}
static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data,
unsigned long ptr)
{
unsigned long flags = user_access_save();
if (!ptr)
handle_null_ptr_deref(data);
else if (data->alignment && !IS_ALIGNED(ptr, data->alignment))
handle_misaligned_access(data, ptr);
else
handle_object_size_mismatch(data, ptr);
user_access_restore(flags);
}
void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,
void *ptr)
{
struct type_mismatch_data_common common_data = {
.location = &data->location,
.type = data->type,
.alignment = data->alignment,
.type_check_kind = data->type_check_kind
};
ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
}
EXPORT_SYMBOL(__ubsan_handle_type_mismatch);
void __ubsan_handle_type_mismatch_v1(struct type_mismatch_data_v1 *data,
void *ptr)
{
struct type_mismatch_data_common common_data = {
.location = &data->location,
.type = data->type,
.alignment = 1UL << data->log_alignment,
.type_check_kind = data->type_check_kind
};
ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
}
EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1);
void __ubsan_handle_out_of_bounds(struct out_of_bounds_data *data, void *index)
{
char index_str[VALUE_LENGTH];
if (suppress_report(&data->location))
return;
ubsan_prologue(&data->location);
val_to_string(index_str, sizeof(index_str), data->index_type, index);
pr_err("index %s is out of range for type %s\n", index_str,
data->array_type->type_name);
ubsan_epilogue();
}
EXPORT_SYMBOL(__ubsan_handle_out_of_bounds);
void __ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data *data,
void *lhs, void *rhs)
{
struct type_descriptor *rhs_type = data->rhs_type;
struct type_descriptor *lhs_type = data->lhs_type;
char rhs_str[VALUE_LENGTH];
char lhs_str[VALUE_LENGTH];
unsigned long ua_flags = user_access_save();
if (suppress_report(&data->location))
goto out;
ubsan_prologue(&data->location);
val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs);
val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs);
if (val_is_negative(rhs_type, rhs))
pr_err("shift exponent %s is negative\n", rhs_str);
else if (get_unsigned_val(rhs_type, rhs) >=
type_bit_width(lhs_type))
pr_err("shift exponent %s is too large for %u-bit type %s\n",
rhs_str,
type_bit_width(lhs_type),
lhs_type->type_name);
else if (val_is_negative(lhs_type, lhs))
pr_err("left shift of negative value %s\n",
lhs_str);
else
pr_err("left shift of %s by %s places cannot be"
" represented in type %s\n",
lhs_str, rhs_str,
lhs_type->type_name);
ubsan_epilogue();
out:
user_access_restore(ua_flags);
}
EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds);
void __ubsan_handle_builtin_unreachable(struct unreachable_data *data)
{
ubsan_prologue(&data->location);
pr_err("calling __builtin_unreachable()\n");
ubsan_epilogue();
panic("can't return from __builtin_unreachable()");
}
EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable);
void __ubsan_handle_load_invalid_value(struct invalid_value_data *data,
void *val)
{
char val_str[VALUE_LENGTH];
if (suppress_report(&data->location))
return;
ubsan_prologue(&data->location);
val_to_string(val_str, sizeof(val_str), data->type, val);
pr_err("load of value %s is not a valid value for type %s\n",
val_str, data->type->type_name);
ubsan_epilogue();
}
EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);