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Avoid undefined behavior in ada_operator_length 

-fsanitize=undefined pointed out this error:

    runtime error: load of value 2887952, which is not a valid value for type 'exp_opcode'

This happens in gdb.ada/complete.exp when processing "complete p
my_glob".  This does not parse, so the Ada parser throws an exception;
but then the code in parse_exp_in_context_1 accepts the expression
anyway.  However, as no elements have been written to the expression,
undefined behavior results.

The fix is to notice this case in parse_exp_in_context_1.  This patch
also adds an assertion to prefixify_expression to enforce this
pre-existing constraint.

gdb/ChangeLog
2018-10-03  Tom Tromey  <tom@tromey.com>

	* parse.c (prefixify_expression): Add assert.
	(parse_exp_in_context_1): Throw exception if the expression is
	empty.
This commit is contained in:
Tom Tromey 2018-08-18 14:51:46 -06:00
parent 4dd1b46077
commit 5e70ee0905
2 changed files with 12 additions and 2 deletions
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8
gdb/ChangeLog
View File

@ -1,3 +1,9 @@
2018-10-03 Tom Tromey <tom@tromey.com>
* parse.c (prefixify_expression): Add assert.
(parse_exp_in_context_1): Throw exception if the expression is
empty.
2018-10-03 Tom Tromey <tom@tromey.com>
* dwarf2read.c (read_signed_leb128): Work in ULONGEST.
@ -14219,7 +14225,7 @@
Update copyright year range in all GDB files.
2018-01-01 Joel Brobecker <brobecker@adacore.com>
2018-01-01, 18 Joel Brobecker <brobecker@adacore.com>
* copyright.py (BY_HAND): Remove gdb/testsuite/gdb.base/step-line.inp
and gdb/testsuite/gdb.base/step-line.c.

6
gdb/parse.c
View File

@ -792,6 +792,7 @@ copy_name (struct stoken token)
int
prefixify_expression (struct expression *expr)
{
gdb_assert (expr->nelts > 0);
int len = sizeof (struct expression) + EXP_ELEM_TO_BYTES (expr->nelts);
struct expression *temp;
int inpos = expr->nelts, outpos = 0;
@ -1205,7 +1206,10 @@ parse_exp_in_context_1 (const char **stringptr, CORE_ADDR pc,
}
CATCH (except, RETURN_MASK_ALL)
{
if (! parse_completion)
/* If parsing for completion, allow this to succeed; but if no
expression elements have been written, then there's nothing
to do, so fail. */
if (! parse_completion || ps.expout_ptr == 0)
throw_exception (except);
}
END_CATCH