From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 107038 invoked by alias); 17 Aug 2015 20:38:51 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 107025 invoked by uid 89); 17 Aug 2015 20:38:50 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.9 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; Mon, 17 Aug 2015 20:38:48 +0000 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (Postfix) with ESMTPS id E2191461D4 for ; Mon, 17 Aug 2015 20:38:46 +0000 (UTC) Received: from pinnacle.lan ([10.3.113.17]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t7HKckZM017628 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA256 bits=256 verify=NO) for ; Mon, 17 Aug 2015 16:38:46 -0400 Date: Mon, 17 Aug 2015 20:38:00 -0000 From: Kevin Buettner To: gdb-patches@sourceware.org Subject: Re: [PATCH] dwarf2read.c: Check type of linkage name attribute prior to decoding Message-ID: <20150817133844.773517b5@pinnacle.lan> In-Reply-To: <20150806153845.26b54eb2@pinnacle.lan> References: <20150803154721.29a6a4ec@pinnacle.lan> <20150806153845.26b54eb2@pinnacle.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-IsSubscribed: yes X-SW-Source: 2015-08/txt/msg00444.txt.bz2 Ping. On Thu, 6 Aug 2015 15:38:45 -0700 Kevin Buettner wrote: > 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 \\(\\)" >