From patchwork Thu Aug 6 22:38:45 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Buettner X-Patchwork-Id: 8078 Received: (qmail 50754 invoked by alias); 7 Aug 2015 02:03:28 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Delivered-To: mailing list gdb-patches@sourceware.org Received: (qmail 50662 invoked by uid 89); 7 Aug 2015 02:03:27 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.7 required=5.0 tests=AWL, BAYES_05, KAM_LAZY_DOMAIN_SECURITY, RP_MATCHES_RCVD, SPF_HELO_PASS autolearn=no version=3.3.2 X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-GCM-SHA384 encrypted) ESMTPS; Fri, 07 Aug 2015 02:03:20 +0000 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (Postfix) with ESMTPS id 328D383F9B for ; Fri, 7 Aug 2015 02:03:19 +0000 (UTC) Received: from pinnacle.lan (ovpn-113-100.phx2.redhat.com [10.3.113.100]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t76MckXx003307 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA256 bits=256 verify=NO) for ; Thu, 6 Aug 2015 18:38:47 -0400 Date: Thu, 6 Aug 2015 15:38:45 -0700 From: Kevin Buettner To: gdb-patches@sourceware.org Subject: Re: [PATCH] dwarf2read.c: Check type of linkage name attribute prior to decoding Message-ID: <20150806153845.26b54eb2@pinnacle.lan> In-Reply-To: References: <20150803154721.29a6a4ec@pinnacle.lan> MIME-Version: 1.0 X-IsSubscribed: yes On Mon, 3 Aug 2015 16:31:08 -0700 Doug Evans wrote: > I wonder, though, if this is a good place for using the dwarf assembler. > Seems so. We just need a MIPS_linkage_name attribute > that isn't a string. The dwarf assembler test would be a lot > smaller. My updated patch, below, does this. > What if there was a wrapper on dwarf2_attr, dwarf2_string_attr > or some such, and it returned either the attribute (if the attribute > is present *and* is a string) or NULL. > And if the attribute is present but not a string it logs a > complaint (standard bad debug info complaint) and returns NULL. I've introduced the wrapper that you recommend and have used it in all places that made sense to me. There were a few spots where using it would have made things more complicated, so I left those alone. Here's the updated change / patch: dwarf2read.c: Check type of string valued attributes prior to decoding. This change introduces a new function, dwarf2_string_attr(), which is a wrapper for dwarf2_attr(). dwarf2read.c has been updated to call dwarf2_string_attr in most instances where a string-valued attribute is decoded to produce a string value. In most cases, it simplifies the code; in some instances, the complexity of the code remains unchanged. I performed this change by looking for instances where the result of DW_STRING was used in an assignment. Many of these had a pattern which (roughly) looks something like this: struct attribute *attr = NULL; attr = dwarf2_attr (die, name, cu); if (attr != NULL && DW_STRING (attr)) { const char *str; ... str = DW_STRING (attr); ... /* Use str in some fashion. */ } Code of this form is transformed to look like this instead: const char *str; str = dwarf2_string_attr (die, name, cu) if (str != NULL) { ... /* Use str in some fashion. */ ... } In addition to invoking dwarf2_attr() and DW_STRING(), dwarf2_string_attr() checks to make sure that the attribute's `form' field matches one of DW_FORM_strp, DW_FORM_string, or DW_FORM_GNU_strp_alt. If it does not match one of these forms, it will return a NULL value in addition to calling complaint(). An earlier version of this patch did this type checking for one particular instance where a string attribute was being decoded. The situation that I was attempting to handle in that earlier patch is this: The Texas Instruments compiler uses the encoding for DW_AT_MIPS_linkage_name for other purposes. TI uses the encoding, 0x2007, for TI_AT_TI_end_line which, unlike DW_AT_MIPS_linkage_name, does not have a string-typed value. In this instance, GDB was attempting to use an integer value as a string pointer, with predictable results. (GDB would die with a segmentation fault.) I've added a test which reproduces the problem that I was orignally wanting to fix. It uses DW_AT_MIPS_linkage name with an associate value which is a string, and again, where the value is a small integer. My test case causes GDB to segfault in an unpatched GDB. There will be two PASSes in a patched GDB. Unpatched GDB: (gdb) ptype f ERROR: Process no longer exists UNRESOLVED: gdb.dwarf2/dw2-bad-mips-linkage-name.exp: ptype f ERROR: Couldn't send ptype g to GDB. UNRESOLVED: gdb.dwarf2/dw2-bad-mips-linkage-name.exp: ptype g Patched GDB: (gdb) ptype f type = bool () (gdb) PASS: gdb.dwarf2/dw2-bad-mips-linkage-name.exp: ptype f ptype g type = bool () (gdb) PASS: gdb.dwarf2/dw2-bad-mips-linkage-name.exp: ptype g I see no regressions on an x86_64 native target. gdb/ChangeLog: * dwarf2read.c (dwarf2_string_attr): New function. (lookup_dwo_unit, process_psymtab_comp_unit_reader) (dwarf2_compute_name, dwarf2_physname, find_file_and_directory) (read_call_site_scope, namespace_name, guess_full_die_structure_name) (anonymous_struct_prefix, prepare_one_comp_unit): Use dwarf2_string_attr in place of dwarf2_attr and DW_STRING. gdb/testsuite/ChangeLog: * gdb.dwarf2/dw2-bad-mips-linkage-name.c: New file. * gdb.dwarf2/dw2-bad-mips-linkage-name.exp: New file. --- gdb/dwarf2read.c | 134 +++++++++++---------- .../gdb.dwarf2/dw2-bad-mips-linkage-name.exp | 72 +++++++++++ 2 files changed, 141 insertions(+), 65 deletions(-) diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c index 7e79342..e017549 100644 --- a/gdb/dwarf2read.c +++ b/gdb/dwarf2read.c @@ -1523,6 +1523,9 @@ static struct attribute *dwarf2_attr (struct die_info *, unsigned int, static struct attribute *dwarf2_attr_no_follow (struct die_info *, unsigned int); +static const char *dwarf2_string_attr (struct die_info *die, unsigned int name, + struct dwarf2_cu *cu); + static int dwarf2_flag_true_p (struct die_info *die, unsigned name, struct dwarf2_cu *cu); @@ -5267,13 +5270,8 @@ lookup_dwo_unit (struct dwarf2_per_cu_data *this_cu, gdb_assert (cu != NULL); /* Yeah, we look dwo_name up again, but it simplifies the code. */ - attr = dwarf2_attr (comp_unit_die, DW_AT_GNU_dwo_name, cu); - gdb_assert (attr != NULL); - dwo_name = DW_STRING (attr); - comp_dir = NULL; - attr = dwarf2_attr (comp_unit_die, DW_AT_comp_dir, cu); - if (attr) - comp_dir = DW_STRING (attr); + dwo_name = dwarf2_string_attr (comp_unit_die, DW_AT_GNU_dwo_name, cu); + comp_dir = dwarf2_string_attr (comp_unit_die, DW_AT_comp_dir, cu); if (this_cu->is_debug_types) { @@ -5935,7 +5933,6 @@ process_psymtab_comp_unit_reader (const struct die_reader_specs *reader, struct objfile *objfile = cu->objfile; struct gdbarch *gdbarch = get_objfile_arch (objfile); struct dwarf2_per_cu_data *per_cu = cu->per_cu; - struct attribute *attr; CORE_ADDR baseaddr; CORE_ADDR best_lowpc = 0, best_highpc = 0; struct partial_symtab *pst; @@ -5953,18 +5950,14 @@ process_psymtab_comp_unit_reader (const struct die_reader_specs *reader, cu->list_in_scope = &file_symbols; /* Allocate a new partial symbol table structure. */ - attr = dwarf2_attr (comp_unit_die, DW_AT_name, cu); - if (attr == NULL || !DW_STRING (attr)) + filename = dwarf2_string_attr (comp_unit_die, DW_AT_name, cu); + if (filename == NULL) filename = ""; - else - filename = DW_STRING (attr); pst = create_partial_symtab (per_cu, filename); /* This must be done before calling dwarf2_build_include_psymtabs. */ - attr = dwarf2_attr (comp_unit_die, DW_AT_comp_dir, cu); - if (attr != NULL) - pst->dirname = DW_STRING (attr); + pst->dirname = dwarf2_string_attr (comp_unit_die, DW_AT_comp_dir, cu); baseaddr = ANOFFSET (objfile->section_offsets, SECT_OFF_TEXT (objfile)); @@ -8457,13 +8450,13 @@ dwarf2_compute_name (const char *name, to be able to reference. Ideally, we want the user to be able to reference this entity using either natural or linkage name, but we haven't started looking at this enhancement yet. */ - struct attribute *attr; + const char *name; - attr = dwarf2_attr (die, DW_AT_linkage_name, cu); - if (attr == NULL) - attr = dwarf2_attr (die, DW_AT_MIPS_linkage_name, cu); - if (attr && DW_STRING (attr)) - return DW_STRING (attr); + name = dwarf2_string_attr (die, DW_AT_linkage_name, cu); + if (name == NULL) + name = dwarf2_string_attr (die, DW_AT_MIPS_linkage_name, cu); + if (name != NULL) + return name; } /* These are the only languages we know how to qualify names in. */ @@ -8716,18 +8709,16 @@ dwarf2_physname (const char *name, struct die_info *die, struct dwarf2_cu *cu) back_to = make_cleanup (null_cleanup, NULL); - attr = dwarf2_attr (die, DW_AT_linkage_name, cu); - if (!attr) - attr = dwarf2_attr (die, DW_AT_MIPS_linkage_name, cu); + mangled = dwarf2_string_attr (die, DW_AT_linkage_name, cu); + if (mangled == NULL) + mangled = dwarf2_string_attr (die, DW_AT_MIPS_linkage_name, cu); /* DW_AT_linkage_name is missing in some cases - depend on what GDB has computed. */ - if (attr && DW_STRING (attr)) + if (mangled != NULL) { char *demangled; - mangled = DW_STRING (attr); - /* Use DMGL_RET_DROP for C++ template functions to suppress their return type. It is easier for GDB users to search for such functions as `name(params)' than `long name(params)'. In such case the minimal @@ -9038,24 +9029,14 @@ static void find_file_and_directory (struct die_info *die, struct dwarf2_cu *cu, const char **name, const char **comp_dir) { - struct attribute *attr; - - *name = NULL; - *comp_dir = NULL; - /* Find the filename. Do not use dwarf2_name here, since the filename is not a source language identifier. */ - attr = dwarf2_attr (die, DW_AT_name, cu); - if (attr) - { - *name = DW_STRING (attr); - } + *name = dwarf2_string_attr (die, DW_AT_name, cu); + *comp_dir = dwarf2_string_attr (die, DW_AT_comp_dir, cu); - attr = dwarf2_attr (die, DW_AT_comp_dir, cu); - if (attr) - *comp_dir = DW_STRING (attr); - else if (producer_is_gcc_lt_4_3 (cu) && *name != NULL - && IS_ABSOLUTE_PATH (*name)) + if (*comp_dir == NULL + && producer_is_gcc_lt_4_3 (cu) && *name != NULL + && IS_ABSOLUTE_PATH (*name)) { char *d = ldirname (*name); @@ -11697,17 +11678,17 @@ read_call_site_scope (struct die_info *die, struct dwarf2_cu *cu) gdb_assert (target_cu->objfile == objfile); if (die_is_declaration (target_die, target_cu)) { - const char *target_physname = NULL; - struct attribute *target_attr; + const char *target_physname; /* Prefer the mangled name; otherwise compute the demangled one. */ - target_attr = dwarf2_attr (target_die, DW_AT_linkage_name, target_cu); - if (target_attr == NULL) - target_attr = dwarf2_attr (target_die, DW_AT_MIPS_linkage_name, - target_cu); - if (target_attr != NULL && DW_STRING (target_attr) != NULL) - target_physname = DW_STRING (target_attr); - else + target_physname = dwarf2_string_attr (target_die, + DW_AT_linkage_name, + target_cu); + if (target_physname == NULL) + target_physname = dwarf2_string_attr (target_die, + DW_AT_MIPS_linkage_name, + target_cu); + if (target_physname == NULL) target_physname = dwarf2_physname (NULL, target_die, target_cu); if (target_physname == NULL) complaint (&symfile_complaints, @@ -14177,10 +14158,8 @@ namespace_name (struct die_info *die, int *is_anonymous, struct dwarf2_cu *cu) { /* We don't use dwarf2_name here so that we can detect the absence of a name -> anonymous namespace. */ - struct attribute *attr = dwarf2_attr (die, DW_AT_name, cu); + name = dwarf2_string_attr (die, DW_AT_name, cu); - if (attr != NULL) - name = DW_STRING (attr); if (name != NULL) break; } @@ -17083,6 +17062,33 @@ dwarf2_attr_no_follow (struct die_info *die, unsigned int name) return NULL; } +/* Return the string associated with a string-typed attribute, or NULL if it + is either not found or is of an incorrect type. */ + +static const char * +dwarf2_string_attr (struct die_info *die, unsigned int name, struct dwarf2_cu *cu) +{ + struct attribute *attr; + const char *str = NULL; + + attr = dwarf2_attr (die, name, cu); + + if (attr != NULL) + { + if (attr->form == DW_FORM_strp || attr->form == DW_FORM_string + || attr->form == DW_FORM_GNU_strp_alt) + str = DW_STRING (attr); + else + complaint (&symfile_complaints, + _("string type expected for attribute %s for " + "DIE at 0x%x in module %s"), + dwarf_attr_name (name), die->offset.sect_off, + objfile_name (cu->objfile)); + } + + return str; +} + /* Return non-zero iff the attribute NAME is defined for the given DIE, and holds a non-zero value. This function should only be used for DW_FORM_flag or DW_FORM_flag_present attributes. */ @@ -19140,16 +19146,17 @@ guess_full_die_structure_name (struct die_info *die, struct dwarf2_cu *cu) { if (child->tag == DW_TAG_subprogram) { - struct attribute *attr; + const char *linkage_name; - attr = dwarf2_attr (child, DW_AT_linkage_name, cu); - if (attr == NULL) - attr = dwarf2_attr (child, DW_AT_MIPS_linkage_name, cu); - if (attr != NULL) + linkage_name = dwarf2_string_attr (child, DW_AT_linkage_name, cu); + if (linkage_name == NULL) + linkage_name = dwarf2_string_attr (child, DW_AT_MIPS_linkage_name, + cu); + if (linkage_name != NULL) { char *actual_name = language_class_name_from_physname (cu->language_defn, - DW_STRING (attr)); + linkage_name); char *name = NULL; if (actual_name != NULL) @@ -19197,8 +19204,7 @@ anonymous_struct_prefix (struct die_info *die, struct dwarf2_cu *cu) && die->tag != DW_TAG_structure_type && die->tag != DW_TAG_union_type) return NULL; - attr = dwarf2_attr (die, DW_AT_name, cu); - if (attr != NULL && DW_STRING (attr) != NULL) + if (dwarf2_string_attr (die, DW_AT_name, cu) != NULL) return NULL; attr = dwarf2_attr (die, DW_AT_linkage_name, cu); @@ -22069,9 +22075,7 @@ prepare_one_comp_unit (struct dwarf2_cu *cu, struct die_info *comp_unit_die, cu->language_defn = language_def (cu->language); } - attr = dwarf2_attr (comp_unit_die, DW_AT_producer, cu); - if (attr) - cu->producer = DW_STRING (attr); + cu->producer = dwarf2_string_attr (comp_unit_die, DW_AT_producer, cu); } /* Release one cached compilation unit, CU. We unlink it from the tree diff --git a/gdb/testsuite/gdb.dwarf2/dw2-bad-mips-linkage-name.exp b/gdb/testsuite/gdb.dwarf2/dw2-bad-mips-linkage-name.exp new file mode 100644 index 0000000..77f6175 --- /dev/null +++ b/gdb/testsuite/gdb.dwarf2/dw2-bad-mips-linkage-name.exp @@ -0,0 +1,72 @@ +# Copyright 2015 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 dwarf.exp + +# This test can only be run on targets which support DWARF-2 and use gas. +if {![dwarf2_support]} { + return 0 +} + +standard_testfile dw2-bad-mips-linkage-name.c dw2-bad-mips-linkage-name.S + +# Set up the DWARF for the test. + +set asm_file [standard_output_file $srcfile2] +Dwarf::assemble $asm_file { + cu {} { + DW_TAG_compile_unit { + {DW_AT_language @DW_LANG_C} + {DW_AT_name dw2-bad-mips-linkage-name.c} + {DW_AT_comp_dir /tmp} + + } { + declare_labels b_l + + b_l: DW_TAG_base_type { + {DW_AT_byte_size 1 DW_FORM_sdata} + {DW_AT_encoding @DW_ATE_signed} + {DW_AT_name bool} + } + DW_TAG_subprogram { + {name f} + {low_pc f addr} + {high_pc f_end_lbl addr} + {type :$b_l} + {DW_AT_MIPS_linkage_name _Z1fv} + } + DW_TAG_subprogram { + {name g} + {low_pc g addr} + {high_pc g_end_lbl addr} + {type :$b_l} + {DW_AT_MIPS_linkage_name 42 DW_FORM_data1} + } + } + } +} + +if { [prepare_for_testing ${testfile}.exp ${testfile} \ + [list $srcfile $asm_file] {nodebug}] } { + return -1 +} + +# A successful run will have two PASSes. A GDB that's lacking +# attribute type checking will segfault at some point. It doesn't +# much matter what we test here, so long as we do something to make +# sure that the DWARF is read. + +gdb_test "ptype f" " = bool \\(\\)" +gdb_test "ptype g" " = bool \\(\\)"