From c1b5a1a6e732a65350af930c499b23018f8663cc Mon Sep 17 00:00:00 2001 From: Joel Brobecker Date: Mon, 8 Dec 2014 10:37:00 -0500 Subject: [PATCH] Internal error trying to print uninitialized string. Trying to print the value of a string whose size is not known at compile-time before it gets assigned a value can lead to the following internal error: (gdb) p my_str $1 = /[...]/utils.c:1089: internal-error: virtual memory exhausted. What happens is that my_str is described as a reference to an array type whose bounds are dynamic. During the read of that variable's value (in default_read_var_value), we end up resolving dynamic types which, for reference types, makes us also resolve the target of that reference type. This means we resolve our variable to a reference to an array whose bounds are undefined, and unfortunately very far appart. So, when we pass that value to ada-valprint, and in particular to da_val_print_ref, we eventually try to allocate too large of a buffer corresponding to the (bogus) size of our array, hence the internal error. This patch fixes the problem by adding a size_check before trying to print the dereferenced value. To perform this check, a function that was previously specific to ada-lang.c (check_size) gets exported, and renamed to something less prone to name collisions (ada_ensure_varsize_limit). gdb/ChangeLog: * ada-lang.h (ada_ensure_varsize_limit): Declare. * ada-lang.c (check_size): Remove advance declaration. (ada_ensure_varsize_limit): Renames check_size. Replace calls to check_size by calls to ada_ensure_varsize_limit throughout. * ada-valprint.c (ada_val_print_ref): Add call to ada_ensure_varsize_limit. Add comment explaining why. gdb/testsuite/ChangeLog: * gdb.ada/str_uninit: New testcase. --- gdb/ChangeLog | 10 ++++++ gdb/ada-lang.c | 16 ++++----- gdb/ada-lang.h | 2 ++ gdb/ada-valprint.c | 6 ++++ gdb/testsuite/ChangeLog | 4 +++ gdb/testsuite/gdb.ada/str_uninit.exp | 40 ++++++++++++++++++++++ gdb/testsuite/gdb.ada/str_uninit/parse.adb | 22 ++++++++++++ gdb/testsuite/gdb.ada/str_uninit/pck.adb | 28 +++++++++++++++ gdb/testsuite/gdb.ada/str_uninit/pck.ads | 24 +++++++++++++ 9 files changed, 143 insertions(+), 9 deletions(-) create mode 100644 gdb/testsuite/gdb.ada/str_uninit.exp create mode 100644 gdb/testsuite/gdb.ada/str_uninit/parse.adb create mode 100644 gdb/testsuite/gdb.ada/str_uninit/pck.adb create mode 100644 gdb/testsuite/gdb.ada/str_uninit/pck.ads diff --git a/gdb/ChangeLog b/gdb/ChangeLog index c12de3a0285..079be7772d7 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,13 @@ +2014-12-13 Joel Brobecker + + * ada-lang.h (ada_ensure_varsize_limit): Declare. + * ada-lang.c (check_size): Remove advance declaration. + (ada_ensure_varsize_limit): Renames check_size. + Replace calls to check_size by calls to ada_ensure_varsize_limit + throughout. + * ada-valprint.c (ada_val_print_ref): Add call to + ada_ensure_varsize_limit. Add comment explaining why. + 2014-12-13 Joel Brobecker * utils.c (make_hex_string): Replace use of sprintf by use of diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c index 69b43f62f34..a45e770d786 100644 --- a/gdb/ada-lang.c +++ b/gdb/ada-lang.c @@ -232,8 +232,6 @@ static int ada_is_direct_array_type (struct type *); static void ada_language_arch_info (struct gdbarch *, struct language_arch_info *); -static void check_size (const struct type *); - static struct value *ada_index_struct_field (int, struct value *, int, struct type *); @@ -678,7 +676,7 @@ coerce_unspec_val_to_type (struct value *val, struct type *type) /* Make sure that the object size is not unreasonable before trying to allocate some memory for it. */ - check_size (type); + ada_ensure_varsize_limit (type); if (value_lazy (val) || TYPE_LENGTH (type) > TYPE_LENGTH (value_type (val))) @@ -740,8 +738,8 @@ lim_warning (const char *format, ...) i.e. if it would be a bad idea to allocate a value of this type in GDB. */ -static void -check_size (const struct type *type) +void +ada_ensure_varsize_limit (const struct type *type) { if (TYPE_LENGTH (type) > varsize_limit) error (_("object size is larger than varsize-limit")); @@ -2052,7 +2050,7 @@ ada_coerce_to_simple_array (struct value *arr) if (arrVal == NULL) error (_("Bounds unavailable for null array pointer.")); - check_size (TYPE_TARGET_TYPE (value_type (arrVal))); + ada_ensure_varsize_limit (TYPE_TARGET_TYPE (value_type (arrVal))); return value_ind (arrVal); } else if (ada_is_constrained_packed_array_type (value_type (arr))) @@ -7917,7 +7915,7 @@ ada_template_to_fixed_record_type_1 (struct type *type, initialized, the type size may be completely bogus and GDB may fail to allocate a value for it. So check the size first before creating the value. */ - check_size (rtype); + ada_ensure_varsize_limit (rtype); /* Using plain value_from_contents_and_address here causes problems because we will end up trying to resolve a type that is currently being @@ -7965,7 +7963,7 @@ ada_template_to_fixed_record_type_1 (struct type *type, large (due to an uninitialized variable in the inferior) that it would cause an overflow when adding it to the record size. */ - check_size (field_type); + ada_ensure_varsize_limit (field_type); TYPE_FIELD_TYPE (rtype, f) = field_type; TYPE_FIELD_NAME (rtype, f) = TYPE_FIELD_NAME (type, f); @@ -10907,7 +10905,7 @@ ada_evaluate_subexp (struct type *expect_type, struct expression *exp, (ada_aligned_type (ada_check_typedef (TYPE_TARGET_TYPE (type)))); } - check_size (type); + ada_ensure_varsize_limit (type); return value_zero (type, lval_memory); } else if (TYPE_CODE (type) == TYPE_CODE_INT) diff --git a/gdb/ada-lang.h b/gdb/ada-lang.h index ba3b9d806ef..964d5690374 100644 --- a/gdb/ada-lang.h +++ b/gdb/ada-lang.h @@ -162,6 +162,8 @@ struct ada_task_info extern void *grow_vect (void *, size_t *, size_t, int); +extern void ada_ensure_varsize_limit (const struct type *type); + extern int ada_get_field_index (const struct type *type, const char *field_name, int maybe_missing); diff --git a/gdb/ada-valprint.c b/gdb/ada-valprint.c index 6f68faebd38..1808cb6156d 100644 --- a/gdb/ada-valprint.c +++ b/gdb/ada-valprint.c @@ -1055,6 +1055,12 @@ ada_val_print_ref (struct type *type, const gdb_byte *valaddr, if (ada_is_tagged_type (value_type (deref_val), 1)) deref_val = ada_tag_value_at_base_address (deref_val); + /* Make sure that the object does not have an unreasonable size + before trying to print it. This can happen for instance with + references to dynamic objects whose contents is uninitialized + (Eg: an array whose bounds are not set yet). */ + ada_ensure_varsize_limit (value_type (deref_val)); + val_print (value_type (deref_val), value_contents_for_printing (deref_val), value_embedded_offset (deref_val), diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog index a0acd983e64..5e8953c3ca2 100644 --- a/gdb/testsuite/ChangeLog +++ b/gdb/testsuite/ChangeLog @@ -1,3 +1,7 @@ +2014-12-13 Joel Brobecker + + * gdb.ada/str_uninit: New testcase. + 2014-12-13 Jan Kratochvil PR symtab/17642 diff --git a/gdb/testsuite/gdb.ada/str_uninit.exp b/gdb/testsuite/gdb.ada/str_uninit.exp new file mode 100644 index 00000000000..706d57d8eca --- /dev/null +++ b/gdb/testsuite/gdb.ada/str_uninit.exp @@ -0,0 +1,40 @@ +# Copyright 2014 Free Software Foundation, Inc. +# +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 3 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see . + +load_lib "ada.exp" + +standard_ada_testfile parse + +if {[gdb_compile_ada "${srcfile}" "${binfile}" executable [list debug ]] != "" } { + return -1 +} + +clean_restart ${testfile} + +set bp_location [gdb_get_line_number "START" ${testdir}/parse.adb] +if ![runto "parse.adb:$bp_location" ] then { + perror "Couldn't run ${testfile}" + return +} + +# Print MY_STR. Since the string has not been initialized, including +# its bounds, anything can happen, including an error. The purpose +# of this test is just to verify that we do not get an _internal_ +# error. +gdb_test "print my_str" " = .*" + +# Just to be certain that the debugger is really still alive, +# try printing something really simple. +gdb_test "print 1235813" " = 1235813" diff --git a/gdb/testsuite/gdb.ada/str_uninit/parse.adb b/gdb/testsuite/gdb.ada/str_uninit/parse.adb new file mode 100644 index 00000000000..85673776322 --- /dev/null +++ b/gdb/testsuite/gdb.ada/str_uninit/parse.adb @@ -0,0 +1,22 @@ +-- Copyright 2014 Free Software Foundation, Inc. +-- +-- This program is free software; you can redistribute it and/or modify +-- it under the terms of the GNU General Public License as published by +-- the Free Software Foundation; either version 3 of the License, or +-- (at your option) any later version. +-- +-- This program is distributed in the hope that it will be useful, +-- but WITHOUT ANY WARRANTY; without even the implied warranty of +-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +-- GNU General Public License for more details. +-- +-- You should have received a copy of the GNU General Public License +-- along with this program. If not, see . + +with Pck; use Pck; + +procedure Parse is + My_Str : String := Foos; -- START +begin + Do_Nothing (My_Str'Address); +end Parse; diff --git a/gdb/testsuite/gdb.ada/str_uninit/pck.adb b/gdb/testsuite/gdb.ada/str_uninit/pck.adb new file mode 100644 index 00000000000..bfc5305c6f3 --- /dev/null +++ b/gdb/testsuite/gdb.ada/str_uninit/pck.adb @@ -0,0 +1,28 @@ +-- Copyright 2011-2014 Free Software Foundation, Inc. +-- +-- This program is free software; you can redistribute it and/or modify +-- it under the terms of the GNU General Public License as published by +-- the Free Software Foundation; either version 3 of the License, or +-- (at your option) any later version. +-- +-- This program is distributed in the hope that it will be useful, +-- but WITHOUT ANY WARRANTY; without even the implied warranty of +-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +-- GNU General Public License for more details. +-- +-- You should have received a copy of the GNU General Public License +-- along with this program. If not, see . + +package body Pck is + + procedure Do_Nothing (A : System.Address) is + begin + null; + end Do_Nothing; + + function Foos return String is + begin + return "string"; + end Foos; + +end Pck; diff --git a/gdb/testsuite/gdb.ada/str_uninit/pck.ads b/gdb/testsuite/gdb.ada/str_uninit/pck.ads new file mode 100644 index 00000000000..e1093752293 --- /dev/null +++ b/gdb/testsuite/gdb.ada/str_uninit/pck.ads @@ -0,0 +1,24 @@ +-- Copyright 2011-2014 Free Software Foundation, Inc. +-- +-- This program is free software; you can redistribute it and/or modify +-- it under the terms of the GNU General Public License as published by +-- the Free Software Foundation; either version 3 of the License, or +-- (at your option) any later version. +-- +-- This program is distributed in the hope that it will be useful, +-- but WITHOUT ANY WARRANTY; without even the implied warranty of +-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +-- GNU General Public License for more details. +-- +-- You should have received a copy of the GNU General Public License +-- along with this program. If not, see . + +with System; + +package Pck is + + procedure Do_Nothing (A : System.Address); + + function Foos return String; + +end Pck; -- 2.30.2