* PR28979, internal error in demand_empty_rest_of_line
@ 2022-03-20 12:44 Alan Modra
0 siblings, 0 replies; only message in thread
From: Alan Modra @ 2022-03-20 12:44 UTC (permalink / raw)
To: binutils
The change in read_a_source_file prevents the particular testcase in
the PR from triggering the assertion in demand_empty_rest_of_line.
I've also removed the assertion. Nothing much goes wrong with gas if
something else triggers it, so it's not worthy of an abort.
I've also changed my previous patch to ignore_rest_of_line to allow
that function to increment input_line_pointer past buffer_limit, like
demand_empty_rest_of_line: The two functions ought to behave the
same in that respect. Finally, demand_empty_rest_of_line gets a
little hardening to prevent accesses past buffer_limit plus one.
PR 28979
* read.c (read_a_source_file): Calculate known size for sbuf
rather than calling strlen.
(demand_empty_rest_of_line): Remove "know" check. Expand comment.
Don't dereference input_line_pointer when past buffer_limit.
(ignore_rest_of_line): Allow input_line_pointer to increment to
buffer_limit plus one. Expand comment.
diff --git a/gas/read.c b/gas/read.c
index e9a300fe10c..7723ee7ba76 100644
--- a/gas/read.c
+++ b/gas/read.c
@@ -1391,6 +1391,7 @@ read_a_source_file (const char *name)
if (size < space)
{
new_tmp[size] = 0;
+ new_length = new_tmp + size - new_buf;
break;
}
@@ -1408,7 +1409,6 @@ read_a_source_file (const char *name)
actual macro expansion (possibly nested) and other
input expansion work. Beware that in messages, line
numbers and possibly file names will be incorrect. */
- new_length = strlen (new_buf);
sb_build (&sbuf, new_length);
sb_add_buffer (&sbuf, new_buf, new_length);
input_scrub_include_sb (&sbuf, input_line_pointer, 0);
@@ -3950,12 +3950,19 @@ s_weakref (int ignore ATTRIBUTE_UNUSED)
\f
/* Verify that we are at the end of a line. If not, issue an error and
- skip to EOL. */
+ skip to EOL. This function may leave input_line_pointer one past
+ buffer_limit, so should not be called from places that may
+ dereference input_line_pointer unconditionally. Note that when the
+ gas parser is switched to handling a string (where buffer_limit
+ should be the size of the string excluding the NUL terminator) this
+ will be one past the NUL; is_end_of_line(0) returns true. */
void
demand_empty_rest_of_line (void)
{
SKIP_WHITESPACE ();
+ if (input_line_pointer > buffer_limit)
+ return;
if (is_end_of_line[(unsigned char) *input_line_pointer])
input_line_pointer++;
else
@@ -3968,18 +3975,19 @@ demand_empty_rest_of_line (void)
*input_line_pointer);
ignore_rest_of_line ();
}
-
/* Return pointing just after end-of-line. */
- know (is_end_of_line[(unsigned char) input_line_pointer[-1]]);
}
/* Silently advance to the end of line. Use this after already having
- issued an error about something bad. */
+ issued an error about something bad. Like demand_empty_rest_of_line,
+ this function may leave input_line_pointer one after buffer_limit;
+ Don't call it from within expression parsing code in an attempt to
+ silence further errors. */
void
ignore_rest_of_line (void)
{
- while (input_line_pointer < buffer_limit)
+ while (input_line_pointer <= buffer_limit)
if (is_end_of_line[(unsigned char) *input_line_pointer++])
break;
/* Return pointing just after end-of-line. */
--
Alan Modra
Australia Development Lab, IBM
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