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Add a warning if an emtpty SHT_REL, SHT_RELA or SHT_PROGBITS section is detected. Disable all warnings unless the (new) lint mode is enabled.

Browse Source 
* readelf.c (warn): New function - like elfcomm.c version but only
	produces output if warnings are enabled.
	(struct options): Add --lint and --enable-checks.
	(usage): Add entry for --lint.
	(parse_args): Handle -L.  If checks are enabled but no dumps have
	been selected then enable all dumps.
	(process_section_headers): Replace long if-then-else sequence with
	a switch.  Add warning messages for empty SHT_REL, SHT_RELA and
	SHT_PROGBITS sections.
	(process_file): Do not complain if the file is an archive and lint
	mode has been enabled.
	* elfcomm.c (error): Make the function weak.
	(warn): Likewise.
	* NEWS: Mention the new feature.
	* doc/binutils.texi: Document the new feature.
	* dwarf.h (report_leb_status): Add file name and line number
	parameters.  Include them in the diagnostic output.
	(READ_ULEB): Pass file and line number to report_leb_status.
	(READ_SLEB): Likewise.
	* dwarf.c (read_and_print_leb128): Pass file and line number to
	report_leb_status.
	* testsuite/binutils-all/readelf.exp: Add test of new feature.
	* testsuite/binutils-all/zero-sec.s: New test source file.
	* testsuite/binutils-all/zero-sec.r: Expected output from new
	test.
This commit is contained in:
Nick Clifton 2020-04-29 16:01:40 +01:00
parent fc49bc7237
commit 1b51340159
10 changed files with 199 additions and 51 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
binutils/ChangeLog
View File

@ -1,3 +1,31 @@
2020-04-29 Nick Clifton <nickc@redhat.com>
* readelf.c (warn): New function - like elfcomm.c version but only
produces output if warnings are enabled.
(struct options): Add --lint and --enable-checks.
(usage): Add entry for --lint.
(parse_args): Handle -L. If checks are enabled but no dumps have
been selected then enable all dumps.
(process_section_headers): Replace long if-then-else sequence with
a switch. Add warning messages for empty SHT_REL, SHT_RELA and
SHT_PROGBITS sections.
(process_file): Do not complain if the file is an archive and lint
mode has been enabled.
* elfcomm.c (error): Make the function weak.
(warn): Likewise.
* NEWS: Mention the new feature.
* doc/binutils.texi: Document the new feature.
* dwarf.h (report_leb_status): Add file name and line number
parameters. Include them in the diagnostic output.
(READ_ULEB): Pass file and line number to report_leb_status.
(READ_SLEB): Likewise.
* dwarf.c (read_and_print_leb128): Pass file and line number to
report_leb_status.
* testsuite/binutils-all/readelf.exp: Add test of new feature.
* testsuite/binutils-all/zero-sec.s: New test source file.
* testsuite/binutils-all/zero-sec.r: Expected output from new
test.
2020-04-29 Nick Clifton <nickc@redhat.com>
* po/sr.po: Updated Serbian translation.

6
binutils/NEWS
View File

@ -1,5 +1,11 @@
-*- text -*-
* The readelf tool now has a -L or --lint or --enable-checks option which turns
on warning messages about possible problems with the file(s) being examined.
These checks include things like zero-sized sections, which are allowed by
the ELF standard but which nevertheless might be of concern if the user
was expecting them to actually contain something.
Changes in 2.34:
* Binutils now supports debuginfod, an HTTP server for distributing

10
binutils/doc/binutils.texi
View File

@ -4706,6 +4706,7 @@ readelf [@option{-a}|@option{--all}]
[@option{-V}|@option{--version-info}]
[@option{-A}|@option{--arch-specific}]
[@option{-D}|@option{--use-dynamic}]
[@option{-L}|@option{--lint}|@option{--enable-checks}]
[@option{-x} <number or name>|@option{--hex-dump=}<number or name>]
[@option{-p} <number or name>|@option{--string-dump=}<number or name>]
[@option{-R} <number or name>|@option{--relocated-dump=}<number or name>]
@ -4862,6 +4863,15 @@ symbol table sections.
When displaying relocations, this option makes @command{readelf}
display the dynamic relocations rather than the static relocations.
@item -L
@itemx --lint
@itemx --enable-checks
Displays warning messages about possible problems with the file(s)
being examined. If used on its own then all of the contents of the
file(s) will be examined. If used with one of the dumping options
then the warning messages will only be produced for the things being
displayed.
@item -x <number or name>
@itemx --hex-dump=<number or name>
Displays the contents of the indicated section as a hexadecimal bytes.

2
binutils/dwarf.c
View File

@ -2008,7 +2008,7 @@ read_and_print_leb128 (unsigned char * data,
int status;
dwarf_vma val = read_leb128 (data, end, is_signed, bytes_read, &status);
if (status != 0)
report_leb_status (status);
report_leb_status (status, __FILE__, __LINE__);
else
printf ("%s", dwarf_vmatoa (is_signed ? "d" : "u", val));
}

22
binutils/dwarf.h
View File

@ -263,12 +263,12 @@ extern unsigned char * get_build_id (void *);
#endif
static inline void
report_leb_status (int status)
report_leb_status (int status, const char *file, unsigned long lnum)
{
if ((status & 1) != 0)
error (_("LEB end of data\n"));
error (_("%s:%lu: end of data encountered whilst reading LEB\n"), file, lnum);
else if ((status & 2) != 0)
error (_("LEB value too large\n"));
error (_("%s:%lu: read LEB value is too large to store in destination variable\n"), file, lnum);
}
#define SKIP_ULEB(start, end) \
@ -277,7 +277,8 @@ report_leb_status (int status)
unsigned int _len; \
read_leb128 (start, end, FALSE, &_len, NULL); \
start += _len; \
} while (0)
} \
while (0)
#define SKIP_SLEB(start, end) \
do \
@ -285,7 +286,8 @@ report_leb_status (int status)
unsigned int _len; \
read_leb128 (start, end, TRUE, &_len, NULL); \
start += _len; \
} while (0)
} \
while (0)
#define READ_ULEB(var, start, end) \
do \
@ -299,8 +301,9 @@ report_leb_status (int status)
(var) = _val; \
if ((var) != _val) \
_status |= 2; \
report_leb_status (_status); \
} while (0)
report_leb_status (_status, __FILE__, __LINE__); \
} \
while (0)
#define READ_SLEB(var, start, end) \
do \
@ -314,5 +317,6 @@ report_leb_status (int status)
(var) = _val; \
if ((var) != _val) \
_status |= 2; \
report_leb_status (_status); \
} while (0)
report_leb_status (_status, __FILE__, __LINE__); \
} \
while (0)

9
binutils/elfcomm.c
View File

@ -34,6 +34,15 @@
extern char *program_name;
/* FIXME: This definition really ought to be in ansidecl.h. */
#ifndef ATTRIBUTE_WEAK
#define ATTRIBUTE_WEAK __attribute__((weak))
#endif
/* Allow the following two functions to be overridden if desired. */
void error (const char *, ...) ATTRIBUTE_WEAK;
void warn (const char *, ...) ATTRIBUTE_WEAK;
void
error (const char *message, ...)
{

158
binutils/readelf.c
View File

@ -199,7 +199,8 @@ struct dump_list_entry
/* A dynamic array of flags indicating for which sections a dump
has been requested via command line switches. */
struct dump_data {
struct dump_data
{
dump_type * dump_sects;
unsigned int num_dump_sects;
};
@ -230,6 +231,8 @@ static bfd_boolean do_ctf = FALSE;
static bfd_boolean do_arch = FALSE;
static bfd_boolean do_notes = FALSE;
static bfd_boolean do_archive_index = FALSE;
static bfd_boolean do_checks = FALSE;
static bfd_boolean check_all = FALSE;
static bfd_boolean is_32bit_elf = FALSE;
static bfd_boolean decompress_dumps = FALSE;
@ -384,6 +387,25 @@ bfd_vmatoa (char *fmtch, bfd_vma value)
return ret;
}
/* A version of the warn() function that is disabled if do_checks is not active. */
void
warn (const char *message, ...)
{
va_list args;
if (!do_checks)
return;
/* Try to keep warning messages in sync with the program's normal output. */
fflush (stdout);
va_start (args, message);
fprintf (stderr, _("%s: Warning: "), program_name);
vfprintf (stderr, message, args);
va_end (args);
}
/* Retrieve NMEMB structures, each SIZE bytes long from FILEDATA starting at
OFFSET + the offset of the current archive member, if we are examining an
archive. Put the retrieved data into VAR, if it is not NULL. Otherwise
@ -4478,6 +4500,8 @@ static struct option options[] =
{"relocs", no_argument, 0, 'r'},
{"notes", no_argument, 0, 'n'},
{"dynamic", no_argument, 0, 'd'},
{"lint", no_argument, 0, 'L'},
{"enable-checks", no_argument, 0, 'L'},
{"arch-specific", no_argument, 0, 'A'},
{"version-info", no_argument, 0, 'V'},
{"use-dynamic", no_argument, 0, 'D'},
@ -4525,7 +4549,7 @@ usage (FILE * stream)
-e --headers Equivalent to: -h -l -S\n\
-s --syms Display the symbol table\n\
--symbols An alias for --syms\n\
--dyn-syms Display the dynamic symbol table\n\
--dyn-syms Display the dynamic symbol table\n\
-n --notes Display the core notes (if present)\n\
-r --relocs Display the relocations (if present)\n\
-u --unwind Display the unwind info (if present)\n\
@ -4534,6 +4558,7 @@ usage (FILE * stream)
-A --arch-specific Display architecture specific information (if any)\n\
-c --archive-index Display the symbol/file index in an archive\n\
-D --use-dynamic Use the dynamic section info when displaying symbols\n\
-L --lint|--enable-checks Display warning messages for possible problems\n\
-x --hex-dump=<number|name>\n\
Dump the contents of section <number|name> as bytes\n\
-p --string-dump=<number|name>\n\
@ -4662,7 +4687,7 @@ parse_args (struct dump_data *dumpdata, int argc, char ** argv)
usage (stderr);
while ((c = getopt_long
(argc, argv, "ADHINR:SVWacdeghi:lnp:rstuvw::x:z", options, NULL)) != EOF)
(argc, argv, "ADHILNR:SVWacdeghi:lnp:rstuvw::x:z", options, NULL)) != EOF)
{
switch (c)
{
@ -4736,6 +4761,9 @@ parse_args (struct dump_data *dumpdata, int argc, char ** argv)
case 'c':
do_archive_index = TRUE;
break;
case 'L':
do_checks = TRUE;
break;
case 'x':
request_dump (dumpdata, HEX_DUMP);
break;
@ -4832,7 +4860,18 @@ parse_args (struct dump_data *dumpdata, int argc, char ** argv)
&& !do_histogram && !do_debugging && !do_arch && !do_notes
&& !do_section_groups && !do_archive_index
&& !do_dyn_syms)
usage (stderr);
{
if (do_checks)
{
check_all = TRUE;
do_dynamic = do_syms = do_reloc = do_unwind = do_sections = TRUE;
do_segments = do_header = do_dump = do_version = TRUE;
do_histogram = do_debugging = do_arch = do_notes = TRUE;
do_section_groups = do_archive_index = do_dyn_syms = TRUE;
}
else
usage (stderr);
}
}
static const char *
@ -6277,7 +6316,7 @@ process_section_headers (Filedata * filedata)
while (0)
#define CHECK_ENTSIZE(section, i, type) \
CHECK_ENTSIZE_VALUES (section, i, sizeof (Elf32_External_##type), \
CHECK_ENTSIZE_VALUES (section, i, sizeof (Elf32_External_##type), \
sizeof (Elf64_External_##type))
for (i = 0, section = filedata->section_headers;
@ -6286,8 +6325,11 @@ process_section_headers (Filedata * filedata)
{
char * name = SECTION_NAME (section);
if (section->sh_type == SHT_DYNSYM)
/* Run some sanity checks on the headers and
possibly fill in some file data as well. */
switch (section->sh_type)
{
case SHT_DYNSYM:
if (filedata->dynamic_symbols != NULL)
{
error (_("File contains multiple dynamic symbol tables\n"));
@ -6297,45 +6339,74 @@ process_section_headers (Filedata * filedata)
CHECK_ENTSIZE (section, i, Sym);
filedata->dynamic_symbols
= GET_ELF_SYMBOLS (filedata, section, &filedata->num_dynamic_syms);
}
else if (section->sh_type == SHT_STRTAB
&& streq (name, ".dynstr"))
{
if (filedata->dynamic_strings != NULL)
break;
case SHT_STRTAB:
if (streq (name, ".dynstr"))
{
error (_("File contains multiple dynamic string tables\n"));
continue;
if (filedata->dynamic_strings != NULL)
{
error (_("File contains multiple dynamic string tables\n"));
continue;
}
filedata->dynamic_strings
= (char *) get_data (NULL, filedata, section->sh_offset,
1, section->sh_size, _("dynamic strings"));
filedata->dynamic_strings_length
= filedata->dynamic_strings == NULL ? 0 : section->sh_size;
}
break;
filedata->dynamic_strings
= (char *) get_data (NULL, filedata, section->sh_offset,
1, section->sh_size, _("dynamic strings"));
filedata->dynamic_strings_length
= filedata->dynamic_strings == NULL ? 0 : section->sh_size;
}
else if (section->sh_type == SHT_SYMTAB_SHNDX)
{
elf_section_list * entry = xmalloc (sizeof * entry);
case SHT_SYMTAB_SHNDX:
{
elf_section_list * entry = xmalloc (sizeof * entry);
entry->hdr = section;
entry->next = filedata->symtab_shndx_list;
filedata->symtab_shndx_list = entry;
entry->hdr = section;
entry->next = filedata->symtab_shndx_list;
filedata->symtab_shndx_list = entry;
}
break;
case SHT_SYMTAB:
CHECK_ENTSIZE (section, i, Sym);
break;
case SHT_GROUP:
CHECK_ENTSIZE_VALUES (section, i, GRP_ENTRY_SIZE, GRP_ENTRY_SIZE);
break;
case SHT_REL:
CHECK_ENTSIZE (section, i, Rel);
if (section->sh_size == 0)
warn (_("Section '%s': zero-sized relocation section\n"), name);
break;
case SHT_RELA:
CHECK_ENTSIZE (section, i, Rela);
if (section->sh_size == 0)
warn (_("Section '%s': zero-sized relocation section\n"), name);
break;
case SHT_NOTE:
case SHT_PROGBITS:
if (section->sh_size == 0)
/* This is not illegal according to the ELF standard, but
it might be an indication that something is wrong. */
warn (_("Section '%s': has a size of zero - is this intended ?\n"), name);
break;
default:
break;
}
else if (section->sh_type == SHT_SYMTAB)
CHECK_ENTSIZE (section, i, Sym);
else if (section->sh_type == SHT_GROUP)
CHECK_ENTSIZE_VALUES (section, i, GRP_ENTRY_SIZE, GRP_ENTRY_SIZE);
else if (section->sh_type == SHT_REL)
CHECK_ENTSIZE (section, i, Rel);
else if (section->sh_type == SHT_RELA)
CHECK_ENTSIZE (section, i, Rela);
else if ((do_debugging || do_debug_info || do_debug_abbrevs
|| do_debug_lines || do_debug_pubnames || do_debug_pubtypes
|| do_debug_aranges || do_debug_frames || do_debug_macinfo
|| do_debug_str || do_debug_loc || do_debug_ranges
|| do_debug_addr || do_debug_cu_index || do_debug_links)
&& (const_strneq (name, ".debug_")
|| const_strneq (name, ".zdebug_")))
if ((do_debugging || do_debug_info || do_debug_abbrevs
|| do_debug_lines || do_debug_pubnames || do_debug_pubtypes
|| do_debug_aranges || do_debug_frames || do_debug_macinfo
|| do_debug_str || do_debug_loc || do_debug_ranges
|| do_debug_addr || do_debug_cu_index || do_debug_links)
&& (const_strneq (name, ".debug_")
|| const_strneq (name, ".zdebug_")))
{
if (name[1] == 'z')
name += sizeof (".zdebug_") - 1;
@ -20646,7 +20717,7 @@ process_file (char * file_name)
}
else
{
if (do_archive_index)
if (do_archive_index && !check_all)
error (_("File %s is not an archive so its index cannot be displayed.\n"),
file_name);
@ -20712,9 +20783,14 @@ main (int argc, char ** argv)
parse_args (& cmdline, argc, argv);
if (optind < (argc - 1))
/* When displaying information for more than one file,
prefix the information with the file name. */
show_name = TRUE;
else if (optind >= argc)
{
/* Ensure that the warning is always displayed. */
do_checks = TRUE;
warn (_("Nothing to do.\n"));
usage (stderr);
}

11
binutils/testsuite/binutils-all/readelf.exp
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@ -506,4 +506,15 @@ if {![binutils_assemble $srcdir/$subdir/dwo.s tmpdir/dwo.o]} then {
readelf_test {--debug-dump=links} $tempfile readelf.k2 {}
}
if {![binutils_assemble $srcdir/$subdir/zero-sec.s tmpdir/zero-sec.o]} then {
unresolved "readelf --enable-checks (failed to assemble zero-sec.s)"
} else {
if ![is_remote host] {
set tempfile tmpdir/zero-sec.o
} else {
set tempfile [remote_download host tmpdir/zero-sec.o]
}
readelf_test {--enable-checks --sections --wide} $tempfile zero-sec.r {}
}

3
binutils/testsuite/binutils-all/zero-sec.r Normal file
View File

@ -0,0 +1,3 @@
#...
.*Warning: Section '.*': has a size of zero - is this intended.*
#...

1
binutils/testsuite/binutils-all/zero-sec.s Normal file
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@ -0,0 +1 @@
.data