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gold patch committed: Don't crash with weird linker script
- From: Ian Lance Taylor <iant at google dot com>
- To: binutils at sourceware dot org
- Date: Fri, 08 Jul 2011 23:35:15 -0700
- Subject: gold patch committed: Don't crash with weird linker script
In PR 11985 Nick asks what gold should do when using a weird linker
script which discards key sections. I suppose I think that the general
goal should be to honor the linker script as much as possible. That is
what this patch does: if the linker script discards sections like
.dynamic or .interp, gold just carries on and does the best it can.
Committed to mainline.
Ian
2011-07-08 Ian Lance Taylor <iant@google.com>
PR gold/11985
* layout.cc (Layout::create_initial_dynamic_sections): Don't crash
if linker script discards key sections.
(Layout::create_dynamic_symtab): Likewise.
(Layout::assign_local_dynsym_offsets): Likewise.
(Layout::sized_create_version_sections): Likewise.
(Layout::create_interp): Likewise.
(Layout::finish_dynamic_section): Likewise.
(Layout::set_dynamic_symbol_size): Likewise.
Index: layout.cc
===================================================================
RCS file: /cvs/src/src/gold/layout.cc,v
retrieving revision 1.213
diff -p -u -r1.213 layout.cc
--- layout.cc 8 Jul 2011 22:48:08 -0000 1.213
+++ layout.cc 9 Jul 2011 06:30:56 -0000
@@ -1786,15 +1786,20 @@ Layout::create_initial_dynamic_sections(
false, ORDER_RELRO,
true);
- this->dynamic_symbol_ =
- symtab->define_in_output_data("_DYNAMIC", NULL, Symbol_table::PREDEFINED,
- this->dynamic_section_, 0, 0,
- elfcpp::STT_OBJECT, elfcpp::STB_LOCAL,
- elfcpp::STV_HIDDEN, 0, false, false);
+ // A linker script may discard .dynamic, so check for NULL.
+ if (this->dynamic_section_ != NULL)
+ {
+ this->dynamic_symbol_ =
+ symtab->define_in_output_data("_DYNAMIC", NULL,
+ Symbol_table::PREDEFINED,
+ this->dynamic_section_, 0, 0,
+ elfcpp::STT_OBJECT, elfcpp::STB_LOCAL,
+ elfcpp::STV_HIDDEN, 0, false, false);
- this->dynamic_data_ = new Output_data_dynamic(&this->dynpool_);
+ this->dynamic_data_ = new Output_data_dynamic(&this->dynpool_);
- this->dynamic_section_->add_output_section_data(this->dynamic_data_);
+ this->dynamic_section_->add_output_section_data(this->dynamic_data_);
+ }
}
// For each output section whose name can be represented as C symbol,
@@ -3708,20 +3713,27 @@ Layout::create_dynamic_symtab(const Inpu
ORDER_DYNAMIC_LINKER,
false);
- Output_section_data* odata = new Output_data_fixed_space(index * symsize,
- align,
- "** dynsym");
- dynsym->add_output_section_data(odata);
-
- dynsym->set_info(local_symcount);
- dynsym->set_entsize(symsize);
- dynsym->set_addralign(align);
+ // Check for NULL as a linker script may discard .dynsym.
+ if (dynsym != NULL)
+ {
+ Output_section_data* odata = new Output_data_fixed_space(index * symsize,
+ align,
+ "** dynsym");
+ dynsym->add_output_section_data(odata);
+
+ dynsym->set_info(local_symcount);
+ dynsym->set_entsize(symsize);
+ dynsym->set_addralign(align);
- this->dynsym_section_ = dynsym;
+ this->dynsym_section_ = dynsym;
+ }
Output_data_dynamic* const odyn = this->dynamic_data_;
- odyn->add_section_address(elfcpp::DT_SYMTAB, dynsym);
- odyn->add_constant(elfcpp::DT_SYMENT, symsize);
+ if (odyn != NULL)
+ {
+ odyn->add_section_address(elfcpp::DT_SYMTAB, dynsym);
+ odyn->add_constant(elfcpp::DT_SYMENT, symsize);
+ }
// If there are more than SHN_LORESERVE allocated sections, we
// create a .dynsym_shndx section. It is possible that we don't
@@ -3738,20 +3750,23 @@ Layout::create_dynamic_symtab(const Inpu
elfcpp::SHF_ALLOC,
false, ORDER_DYNAMIC_LINKER, false);
- this->dynsym_xindex_ = new Output_symtab_xindex(index);
+ if (dynsym_xindex != NULL)
+ {
+ this->dynsym_xindex_ = new Output_symtab_xindex(index);
- dynsym_xindex->add_output_section_data(this->dynsym_xindex_);
+ dynsym_xindex->add_output_section_data(this->dynsym_xindex_);
- dynsym_xindex->set_link_section(dynsym);
- dynsym_xindex->set_addralign(4);
- dynsym_xindex->set_entsize(4);
+ dynsym_xindex->set_link_section(dynsym);
+ dynsym_xindex->set_addralign(4);
+ dynsym_xindex->set_entsize(4);
- dynsym_xindex->set_after_input_sections();
+ dynsym_xindex->set_after_input_sections();
- // This tells the driver code to wait until the symbol table has
- // written out before writing out the postprocessing sections,
- // including the .dynsym_shndx section.
- this->any_postprocessing_sections_ = true;
+ // This tells the driver code to wait until the symbol table
+ // has written out before writing out the postprocessing
+ // sections, including the .dynsym_shndx section.
+ this->any_postprocessing_sections_ = true;
+ }
}
// Create the dynamic string table section.
@@ -3763,16 +3778,24 @@ Layout::create_dynamic_symtab(const Inpu
ORDER_DYNAMIC_LINKER,
false);
- Output_section_data* strdata = new Output_data_strtab(&this->dynpool_);
- dynstr->add_output_section_data(strdata);
+ if (dynstr != NULL)
+ {
+ Output_section_data* strdata = new Output_data_strtab(&this->dynpool_);
+ dynstr->add_output_section_data(strdata);
- dynsym->set_link_section(dynstr);
- this->dynamic_section_->set_link_section(dynstr);
+ if (dynsym != NULL)
+ dynsym->set_link_section(dynstr);
+ if (this->dynamic_section_ != NULL)
+ this->dynamic_section_->set_link_section(dynstr);
- odyn->add_section_address(elfcpp::DT_STRTAB, dynstr);
- odyn->add_section_size(elfcpp::DT_STRSZ, dynstr);
+ if (odyn != NULL)
+ {
+ odyn->add_section_address(elfcpp::DT_STRTAB, dynstr);
+ odyn->add_section_size(elfcpp::DT_STRSZ, dynstr);
+ }
- *pdynstr = dynstr;
+ *pdynstr = dynstr;
+ }
// Create the hash tables.
@@ -3793,12 +3816,18 @@ Layout::create_dynamic_symtab(const Inpu
hashlen,
align,
"** hash");
- hashsec->add_output_section_data(hashdata);
+ if (hashsec != NULL && hashdata != NULL)
+ hashsec->add_output_section_data(hashdata);
- hashsec->set_link_section(dynsym);
- hashsec->set_entsize(4);
+ if (hashsec != NULL)
+ {
+ if (dynsym != NULL)
+ hashsec->set_link_section(dynsym);
+ hashsec->set_entsize(4);
+ }
- odyn->add_section_address(elfcpp::DT_HASH, hashsec);
+ if (odyn != NULL)
+ odyn->add_section_address(elfcpp::DT_HASH, hashsec);
}
if (strcmp(parameters->options().hash_style(), "gnu") == 0
@@ -3818,17 +3847,23 @@ Layout::create_dynamic_symtab(const Inpu
hashlen,
align,
"** hash");
- hashsec->add_output_section_data(hashdata);
+ if (hashsec != NULL && hashdata != NULL)
+ hashsec->add_output_section_data(hashdata);
- hashsec->set_link_section(dynsym);
+ if (hashsec != NULL)
+ {
+ if (dynsym != NULL)
+ hashsec->set_link_section(dynsym);
- // For a 64-bit target, the entries in .gnu.hash do not have a
- // uniform size, so we only set the entry size for a 32-bit
- // target.
- if (parameters->target().get_size() == 32)
- hashsec->set_entsize(4);
+ // For a 64-bit target, the entries in .gnu.hash do not have
+ // a uniform size, so we only set the entry size for a
+ // 32-bit target.
+ if (parameters->target().get_size() == 32)
+ hashsec->set_entsize(4);
- odyn->add_section_address(elfcpp::DT_GNU_HASH, hashsec);
+ if (odyn != NULL)
+ odyn->add_section_address(elfcpp::DT_GNU_HASH, hashsec);
+ }
}
}
@@ -3838,7 +3873,8 @@ void
Layout::assign_local_dynsym_offsets(const Input_objects* input_objects)
{
Output_section* dynsym = this->dynsym_section_;
- gold_assert(dynsym != NULL);
+ if (dynsym == NULL)
+ return;
off_t off = dynsym->offset();
@@ -3919,46 +3955,59 @@ Layout::sized_create_version_sections(
ORDER_DYNAMIC_LINKER,
false);
- unsigned char* vbuf;
- unsigned int vsize;
- versions->symbol_section_contents<size, big_endian>(symtab, &this->dynpool_,
- local_symcount,
- dynamic_symbols,
- &vbuf, &vsize);
-
- Output_section_data* vdata = new Output_data_const_buffer(vbuf, vsize, 2,
- "** versions");
-
- vsec->add_output_section_data(vdata);
- vsec->set_entsize(2);
- vsec->set_link_section(this->dynsym_section_);
+ // Check for NULL since a linker script may discard this section.
+ if (vsec != NULL)
+ {
+ unsigned char* vbuf;
+ unsigned int vsize;
+ versions->symbol_section_contents<size, big_endian>(symtab,
+ &this->dynpool_,
+ local_symcount,
+ dynamic_symbols,
+ &vbuf, &vsize);
+
+ Output_section_data* vdata = new Output_data_const_buffer(vbuf, vsize, 2,
+ "** versions");
+
+ vsec->add_output_section_data(vdata);
+ vsec->set_entsize(2);
+ vsec->set_link_section(this->dynsym_section_);
+ }
Output_data_dynamic* const odyn = this->dynamic_data_;
- odyn->add_section_address(elfcpp::DT_VERSYM, vsec);
+ if (odyn != NULL && vsec != NULL)
+ odyn->add_section_address(elfcpp::DT_VERSYM, vsec);
if (versions->any_defs())
{
Output_section* vdsec;
- vdsec= this->choose_output_section(NULL, ".gnu.version_d",
- elfcpp::SHT_GNU_verdef,
- elfcpp::SHF_ALLOC,
- false, ORDER_DYNAMIC_LINKER, false);
-
- unsigned char* vdbuf;
- unsigned int vdsize;
- unsigned int vdentries;
- versions->def_section_contents<size, big_endian>(&this->dynpool_, &vdbuf,
- &vdsize, &vdentries);
-
- Output_section_data* vddata =
- new Output_data_const_buffer(vdbuf, vdsize, 4, "** version defs");
-
- vdsec->add_output_section_data(vddata);
- vdsec->set_link_section(dynstr);
- vdsec->set_info(vdentries);
+ vdsec = this->choose_output_section(NULL, ".gnu.version_d",
+ elfcpp::SHT_GNU_verdef,
+ elfcpp::SHF_ALLOC,
+ false, ORDER_DYNAMIC_LINKER, false);
- odyn->add_section_address(elfcpp::DT_VERDEF, vdsec);
- odyn->add_constant(elfcpp::DT_VERDEFNUM, vdentries);
+ if (vdsec != NULL)
+ {
+ unsigned char* vdbuf;
+ unsigned int vdsize;
+ unsigned int vdentries;
+ versions->def_section_contents<size, big_endian>(&this->dynpool_,
+ &vdbuf, &vdsize,
+ &vdentries);
+
+ Output_section_data* vddata =
+ new Output_data_const_buffer(vdbuf, vdsize, 4, "** version defs");
+
+ vdsec->add_output_section_data(vddata);
+ vdsec->set_link_section(dynstr);
+ vdsec->set_info(vdentries);
+
+ if (odyn != NULL)
+ {
+ odyn->add_section_address(elfcpp::DT_VERDEF, vdsec);
+ odyn->add_constant(elfcpp::DT_VERDEFNUM, vdentries);
+ }
+ }
}
if (versions->any_needs())
@@ -3969,22 +4018,28 @@ Layout::sized_create_version_sections(
elfcpp::SHF_ALLOC,
false, ORDER_DYNAMIC_LINKER, false);
- unsigned char* vnbuf;
- unsigned int vnsize;
- unsigned int vnentries;
- versions->need_section_contents<size, big_endian>(&this->dynpool_,
- &vnbuf, &vnsize,
- &vnentries);
-
- Output_section_data* vndata =
- new Output_data_const_buffer(vnbuf, vnsize, 4, "** version refs");
-
- vnsec->add_output_section_data(vndata);
- vnsec->set_link_section(dynstr);
- vnsec->set_info(vnentries);
+ if (vnsec != NULL)
+ {
+ unsigned char* vnbuf;
+ unsigned int vnsize;
+ unsigned int vnentries;
+ versions->need_section_contents<size, big_endian>(&this->dynpool_,
+ &vnbuf, &vnsize,
+ &vnentries);
+
+ Output_section_data* vndata =
+ new Output_data_const_buffer(vnbuf, vnsize, 4, "** version refs");
+
+ vnsec->add_output_section_data(vndata);
+ vnsec->set_link_section(dynstr);
+ vnsec->set_info(vnentries);
- odyn->add_section_address(elfcpp::DT_VERNEED, vnsec);
- odyn->add_constant(elfcpp::DT_VERNEEDNUM, vnentries);
+ if (odyn != NULL)
+ {
+ odyn->add_section_address(elfcpp::DT_VERNEED, vnsec);
+ odyn->add_constant(elfcpp::DT_VERNEEDNUM, vnentries);
+ }
+ }
}
}
@@ -4011,7 +4066,8 @@ Layout::create_interp(const Target* targ
elfcpp::SHF_ALLOC,
false, ORDER_INTERP,
false);
- osec->add_output_section_data(odata);
+ if (osec != NULL)
+ osec->add_output_section_data(odata);
}
// Add dynamic tags for the PLT and the dynamic relocs. This is
@@ -4117,7 +4173,8 @@ void
Layout::finish_dynamic_section(const Input_objects* input_objects,
const Symbol_table* symtab)
{
- if (!this->script_options_->saw_phdrs_clause())
+ if (!this->script_options_->saw_phdrs_clause()
+ && this->dynamic_section_ != NULL)
{
Output_segment* oseg = this->make_output_segment(elfcpp::PT_DYNAMIC,
(elfcpp::PF_R
@@ -4127,6 +4184,8 @@ Layout::finish_dynamic_section(const Inp
}
Output_data_dynamic* const odyn = this->dynamic_data_;
+ if (odyn == NULL)
+ return;
for (Input_objects::Dynobj_iterator p = input_objects->dynobj_begin();
p != input_objects->dynobj_end();
@@ -4322,7 +4381,11 @@ void
Layout::set_dynamic_symbol_size(const Symbol_table* symtab)
{
Output_data_dynamic* const odyn = this->dynamic_data_;
+ if (odyn == NULL)
+ return;
odyn->finalize_data_size();
+ if (this->dynamic_symbol_ == NULL)
+ return;
off_t data_size = odyn->data_size();
const int size = parameters->target().get_size();
if (size == 32)