On Fri, Nov 23, 2012 at 11:23 AM, Uros Bizjak <ubiz...@gmail.com> wrote:
> On Fri, Nov 23, 2012 at 8:16 PM, H.J. Lu <hjl.to...@gmail.com> wrote:
>> On Fri, Nov 23, 2012 at 10:59 AM, Uros Bizjak <ubiz...@gmail.com> wrote:
>>> Hello!
>>>
>>>> This patch allocates extra 16 bytes for -fsanitize=address so that
>>>> asan won't report read beyond memory buffer. It is used by
>>>> bootstrap-asan. OK to install?
>>>
>>> /* Resize buffer if we allocated substantially too much, or if we
>>> - haven't enough space for the \n-terminator. */
>>> + haven't enough space for the \n-terminator. Allocate extra 16
>>> + bytes for -fsanitize=address. */
>>>
>>> I guess that extra _15_ bytes should be enough? The maximum we need
>>> for SSE stringops is additional 15 bytes, when only the first byte is
>>> allocated in the 16byte bundle.
>>>
>>
>> If we need to clear the extra bytes, clearing 16 bytes can be faster
>> than 16 bytes.
>
> (I assume "... than 15 bytes").
>
> However, this is ideal for the code below, where we add either +16 or
> +1, considering also additional byte for the terminator.
>
> Uros.
Here is the updated patch. I added CLEAR_CPP_PAD_BUFFER to
be used later for valgrind. I have no real preferences for 15 vs 16 extra
bytes.
--
H.J.
---
2012-11-21 H.J. Lu <hongjiu...@intel.com>
PR bootstrap/55380
* charset.c (_cpp_convert_input): Clear CPP_PAD_BUFFER_SIZE
bytes if CLEAR_CPP_PAD_BUFFER isn't 0. Allocate extra
CPP_PAD_BUFFER_SIZE bytes and clear it if CLEAR_CPP_PAD_BUFFER
isn't 0.
* files.c (read_file_guts): Allocate extra CPP_PAD_BUFFER_SIZE
bytes.
* internal.h (CPP_PAD_BUFFER_SIZE): New. Defined to 16 for
-fsanitize=address if __SANITIZE_ADDRESS__ is defined.
(CLEAR_CPP_PAD_BUFFER): New.
diff --git a/libcpp/charset.c b/libcpp/charset.c
index cba19a6..1ca94a1 100644
--- a/libcpp/charset.c
+++ b/libcpp/charset.c
@@ -1709,6 +1709,8 @@ _cpp_convert_input (cpp_reader *pfile, const char *input_c
harset,
to.text = input;
to.asize = size;
to.len = len;
+ if (CLEAR_CPP_PAD_BUFFER)
+ memset (input + size, 0, CPP_PAD_BUFFER_SIZE);
}
else
{
@@ -1731,7 +1733,12 @@ _cpp_convert_input (cpp_reader *pfile, const char *input_
charset,
/* Resize buffer if we allocated substantially too much, or if we
haven't enough space for the \n-terminator. */
if (to.len + 4096 < to.asize || to.len >= to.asize)
- to.text = XRESIZEVEC (uchar, to.text, to.len + 1);
+ {
+ to.text = XRESIZEVEC (uchar, to.text,
+ to.len + CPP_PAD_BUFFER_SIZE + 1);
+ if (CLEAR_CPP_PAD_BUFFER)
+ memset (to.text + to.len + 1, 0, CPP_PAD_BUFFER_SIZE);
+ }
/* If the file is using old-school Mac line endings (\r only),
terminate with another \r, not an \n, so that we do not mistake
diff --git a/libcpp/files.c b/libcpp/files.c
index 9f84d8c..090f928 100644
--- a/libcpp/files.c
+++ b/libcpp/files.c
@@ -671,7 +671,7 @@ read_file_guts (cpp_reader *pfile, _cpp_file *file)
the majority of C source files. */
size = 8 * 1024;
- buf = XNEWVEC (uchar, size + 1);
+ buf = XNEWVEC (uchar, size + CPP_PAD_BUFFER_SIZE + 1);
total = 0;
while ((count = read (file->fd, buf + total, size - total)) > 0)
{
@@ -682,7 +682,7 @@ read_file_guts (cpp_reader *pfile, _cpp_file *file)
if (regular)
break;
size *= 2;
- buf = XRESIZEVEC (uchar, buf, size + 1);
+ buf = XRESIZEVEC (uchar, buf, size + CPP_PAD_BUFFER_SIZE + 1);
}
}
diff --git a/libcpp/internal.h b/libcpp/internal.h
index 312b8b5..bc1f311 100644
--- a/libcpp/internal.h
+++ b/libcpp/internal.h
@@ -77,6 +77,16 @@ struct cset_converter
efficiency, and partly to limit runaway recursion. */
#define CPP_STACK_MAX 200
+/* Allocate extra 16 bytes for -fsanitize=address. */
+#ifdef __SANITIZE_ADDRESS__
+#define CPP_PAD_BUFFER_SIZE 16
+#else
+#define CPP_PAD_BUFFER_SIZE 0
+#endif
+
+/* 1 to clear extra 16 bytes. */
+#define CLEAR_CPP_PAD_BUFFER 0
+
/* Host alignment handling. */
struct dummy
{
