My port of addresssanitizer is based on GCC 4.8.1.
I modify "asan_emit_stack_protection" function in gcc/asan.c for the
following reason:
Sometimes, the stack variable size > 32 Bytes, and after asan
generates code to poison the shadow buffer, it does clear some shadow
buffer but not all before function return.
So I use the way of poisoning to recover the shadow.
Does any of you suffer the problem? It works fine for my platform now.
about line 1050:
#if 0 // I find some false positive for those code
for (l = length; l; l -= 2)
{
offset = base_offset + ((offsets[l - 1] - base_offset)
& ~(ASAN_RED_ZONE_SIZE - HOST_WIDE_INT_1));
if (last_offset + last_size != offset)
{
shadow_mem = adjust_address (shadow_mem, VOIDmode,
(last_offset - prev_offset)
>> ASAN_SHADOW_SHIFT);
prev_offset = last_offset;
asan_clear_shadow (shadow_mem, last_size >> ASAN_SHADOW_SHIFT);
last_offset = offset;
last_size = 0;
}
last_size += base_offset + ((offsets[l - 2] - base_offset)
& ~(ASAN_RED_ZONE_SIZE - HOST_WIDE_INT_1))
- offset;
}
if (last_size)
{
shadow_mem = adjust_address (shadow_mem, VOIDmode,
(last_offset - prev_offset)
>> ASAN_SHADOW_SHIFT);
asan_clear_shadow (shadow_mem, last_size >> ASAN_SHADOW_SHIFT);
}
#else
for (l = length; l; l -= 2)
{
if (l == 2)
cur_shadow_byte = ASAN_STACK_MAGIC_RIGHT;
offset = offsets[l - 1];
if ((offset - base_offset) & (ASAN_RED_ZONE_SIZE - 1))
{
HOST_WIDE_INT aoff
= base_offset + ((offset - base_offset)
& ~(ASAN_RED_ZONE_SIZE - HOST_WIDE_INT_1));
shadow_mem = adjust_address (shadow_mem, VOIDmode,
(aoff - prev_offset)
>> ASAN_SHADOW_SHIFT);
prev_offset = aoff;
aoff += (1 << ASAN_SHADOW_SHIFT) << 2;
asan_clear_shadow (shadow_mem, 4);
offset = aoff;
}
while (offset <= offsets[l - 2] - ASAN_RED_ZONE_SIZE)
{
shadow_mem = adjust_address (shadow_mem, VOIDmode,
(offset - prev_offset)
>> ASAN_SHADOW_SHIFT);
prev_offset = offset;
asan_clear_shadow (shadow_mem, 4);
offset += ASAN_RED_ZONE_SIZE;
}
}
#endif
