binutils-gdb/gdb/exec.h
Sandra Loosemore ecf45d2cc7 PR 20569, segv in follow_exec
The following testcases make GDB crash whenever an invalid sysroot is
provided, when GDB is unable to find a valid path to the symbol file:

 gdb.base/catch-syscall.exp
 gdb.base/execl-update-breakpoints.exp
 gdb.base/foll-exec-mode.exp
 gdb.base/foll-exec.exp
 gdb.base/foll-vfork.exp
 gdb.base/pie-execl.exp
 gdb.multi/bkpt-multi-exec.exp
 gdb.python/py-finish-breakpoint.exp
 gdb.threads/execl.exp
 gdb.threads/non-ldr-exc-1.exp
 gdb.threads/non-ldr-exc-2.exp
 gdb.threads/non-ldr-exc-3.exp
 gdb.threads/non-ldr-exc-4.exp
 gdb.threads/thread-execl.exp

The immediate cause of the segv is that follow_exec is passing a NULL
argument (the result of exec_file_find) to strlen.

However, the problem is deeper than that: follow_exec simply isn't
prepared for the case where sysroot translation fails to locate the
new executable.  Actually all callers of exec_file_find have bugs due
to confusion between host and target pathnames.  This commit attempts
to fix all that.

In terms of the testcases that were formerly segv'ing, GDB now prints
a warning but continues execution of the new program, so that the
tests now mostly FAIL instead.  You could argue the FAILs are due to a
legitimate problem with the test environment setting up the sysroot
translation incorrectly.

A new representative test is added which exercises the ne wwarning
code path even with native testing.

Tested on x86_64 Fedora 23, native and gdbserver.

gdb/ChangeLog:
2016-10-25  Sandra Loosemore  <sandra@codesourcery.com>
	    Luis Machado  <lgustavo@codesourcery.com>
	    Pedro Alves  <palves@redhat.com>

	PR gdb/20569
	* exceptions.c (exception_print_same): Moved here from exec.c.
	* exceptions.h (exception_print_same): Declare.
	* exec.h: Include "symfile-add-flags.h".
	(try_open_exec_file): New declaration.
	* exec.c (exception_print_same): Moved to exceptions.c.
	(try_open_exec_file): New function.
	(exec_file_locate_attach): Rename exec_file and full_exec_path
	variables to avoid confusion between target and host pathnames.
	Move pathname processing logic to exec_file_find.  Do not return
	early if pathname lookup fails; Call try_open_exec_file.
	* infrun.c (follow_exec): Split and rename execd_pathname variable
	to avoid confusion between target and host pathnames.  Warn if
	pathname lookup fails.  Pass target pathname to
	target_follow_exec, not hostpathname.  Call try_open_exec_file.
	* main.c (symbol_file_add_main_adapter): New function.
	(captured_main_1): Use it.
	* solib-svr4.c (open_symbol_file_object): Adjust to pass
	symfile_add_flags to symbol_file_add_main.
	* solib.c (exec_file_find): Incorporate fallback logic for relative
	pathnames formerly in exec_file_locate_attach.
	* symfile.c (symbol_file_add_main, symbol_file_add_main_1):
	Replace 'from_tty' parameter with a symfile_add_file.
	(symbol_file_command): Adjust to pass symfile_add_flags to
	symbol_file_add_main.
	* symfile.h (symbol_file_add_main): Replace 'from_tty' parameter
	with a symfile_add_file.

gdb/testsuite/ChangeLog:
2016-10-25  Luis Machado  <lgustavo@codesourcery.com>

	* gdb.base/exec-invalid-sysroot.exp: New file.
2016-10-26 16:47:46 +01:00

125 lines
4.2 KiB
C

/* Work with executable files, for GDB, the GNU debugger.
Copyright (C) 2003-2016 Free Software Foundation, Inc.
This file is part of GDB.
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 <http://www.gnu.org/licenses/>. */
#ifndef EXEC_H
#define EXEC_H
#include "target.h"
#include "progspace.h"
#include "memrange.h"
#include "symfile-add-flags.h"
struct target_section;
struct target_ops;
struct bfd;
struct objfile;
#define exec_bfd current_program_space->ebfd
#define exec_bfd_mtime current_program_space->ebfd_mtime
#define exec_filename current_program_space->pspace_exec_filename
/* Builds a section table, given args BFD, SECTABLE_PTR, SECEND_PTR.
Returns 0 if OK, 1 on error. */
extern int build_section_table (struct bfd *, struct target_section **,
struct target_section **);
/* Remove all entries from TABLE. */
extern void clear_section_table (struct target_section_table *table);
/* Read from mappable read-only sections of BFD executable files.
Return TARGET_XFER_OK, if read is successful. Return
TARGET_XFER_EOF if read is done. Return TARGET_XFER_E_IO
otherwise. */
extern enum target_xfer_status
exec_read_partial_read_only (gdb_byte *readbuf, ULONGEST offset,
ULONGEST len, ULONGEST *xfered_len);
/* Read or write from mappable sections of BFD executable files.
Request to transfer up to LEN 8-bit bytes of the target sections
defined by SECTIONS and SECTIONS_END. The OFFSET specifies the
starting address.
If SECTION_NAME is not NULL, only access sections with that same
name.
Return the number of bytes actually transfered, or zero when no
data is available for the requested range.
This function is intended to be used from target_xfer_partial
implementations. See target_read and target_write for more
information.
One, and only one, of readbuf or writebuf must be non-NULL. */
extern enum target_xfer_status
section_table_xfer_memory_partial (gdb_byte *,
const gdb_byte *,
ULONGEST, ULONGEST, ULONGEST *,
struct target_section *,
struct target_section *,
const char *);
/* Read from mappable read-only sections of BFD executable files.
Similar to exec_read_partial_read_only, but return
TARGET_XFER_UNAVAILABLE if data is unavailable. */
extern enum target_xfer_status
section_table_read_available_memory (gdb_byte *readbuf, ULONGEST offset,
ULONGEST len, ULONGEST *xfered_len);
/* Set the loaded address of a section. */
extern void exec_set_section_address (const char *, int, CORE_ADDR);
/* Remove all target sections owned by OWNER. */
extern void remove_target_sections (void *owner);
/* Add the sections array defined by [SECTIONS..SECTIONS_END[ to the
current set of target sections. */
extern void add_target_sections (void *owner,
struct target_section *sections,
struct target_section *sections_end);
/* Add the sections of OBJFILE to the current set of target sections.
* OBJFILE owns the new target sections. */
extern void add_target_sections_of_objfile (struct objfile *objfile);
/* Prints info about all sections defined in the TABLE. ABFD is
special cased --- it's filename is omitted; if it is the executable
file, its entry point is printed. */
extern void print_section_info (struct target_section_table *table,
bfd *abfd);
extern void exec_close (void);
/* Helper function that attempts to open the symbol file at EXEC_FILE_HOST.
If successful, it proceeds to add the symbol file as the main symbol file.
ADD_FLAGS is passed on to the function adding the symbol file. */
extern void try_open_exec_file (const char *exec_file_host,
struct inferior *inf,
symfile_add_flags add_flags);
#endif