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.
This commit is contained in:
Sandra Loosemore
Pedro Alves
parent
b15cc25cbe
commit
ecf45d2cc7
14 changed files with 277 additions and 121 deletions
48
gdb/infrun.c
48
gdb/infrun.c
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@ -1077,15 +1077,17 @@ show_follow_exec_mode_string (struct ui_file *file, int from_tty,
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fprintf_filtered (file, _("Follow exec mode is \"%s\".\n"), value);
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}
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/* EXECD_PATHNAME is assumed to be non-NULL. */
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/* EXEC_FILE_TARGET is assumed to be non-NULL. */
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static void
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follow_exec (ptid_t ptid, char *execd_pathname)
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follow_exec (ptid_t ptid, char *exec_file_target)
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{
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struct thread_info *th, *tmp;
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struct inferior *inf = current_inferior ();
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int pid = ptid_get_pid (ptid);
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ptid_t process_ptid;
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char *exec_file_host;
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struct cleanup *old_chain;
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/* This is an exec event that we actually wish to pay attention to.
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Refresh our symbol table to the newly exec'd program, remove any
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@ -1155,7 +1157,7 @@ follow_exec (ptid_t ptid, char *execd_pathname)
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process_ptid = pid_to_ptid (pid);
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printf_unfiltered (_("%s is executing new program: %s\n"),
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target_pid_to_str (process_ptid),
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execd_pathname);
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exec_file_target);
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/* We've followed the inferior through an exec. Therefore, the
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inferior has essentially been killed & reborn. */
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@ -1164,14 +1166,17 @@ follow_exec (ptid_t ptid, char *execd_pathname)
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breakpoint_init_inferior (inf_execd);
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if (*gdb_sysroot != '\0')
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{
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char *name = exec_file_find (execd_pathname, NULL);
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exec_file_host = exec_file_find (exec_file_target, NULL);
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old_chain = make_cleanup (xfree, exec_file_host);
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execd_pathname = (char *) alloca (strlen (name) + 1);
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strcpy (execd_pathname, name);
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xfree (name);
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}
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/* If we were unable to map the executable target pathname onto a host
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pathname, tell the user that. Otherwise GDB's subsequent behavior
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is confusing. Maybe it would even be better to stop at this point
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so that the user can specify a file manually before continuing. */
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if (exec_file_host == NULL)
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warning (_("Could not load symbols for executable %s.\n"
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"Do you need \"set sysroot\"?"),
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exec_file_target);
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/* Reset the shared library package. This ensures that we get a
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shlib event when the child reaches "_start", at which point the
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@ -1193,7 +1198,7 @@ follow_exec (ptid_t ptid, char *execd_pathname)
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inf = add_inferior_with_spaces ();
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inf->pid = pid;
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target_follow_exec (inf, execd_pathname);
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target_follow_exec (inf, exec_file_target);
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set_current_inferior (inf);
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set_current_program_space (inf->pspace);
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@ -1212,21 +1217,14 @@ follow_exec (ptid_t ptid, char *execd_pathname)
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gdb_assert (current_program_space == inf->pspace);
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/* That a.out is now the one to use. */
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exec_file_attach (execd_pathname, 0);
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/* Attempt to open the exec file. SYMFILE_DEFER_BP_RESET is used
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because the proper displacement for a PIE (Position Independent
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Executable) main symbol file will only be computed by
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solib_create_inferior_hook below. breakpoint_re_set would fail
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to insert the breakpoints with the zero displacement. */
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try_open_exec_file (exec_file_host, inf, SYMFILE_DEFER_BP_RESET);
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/* SYMFILE_DEFER_BP_RESET is used as the proper displacement for PIE
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(Position Independent Executable) main symbol file will get applied by
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solib_create_inferior_hook below. breakpoint_re_set would fail to insert
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the breakpoints with the zero displacement. */
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symbol_file_add (execd_pathname,
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(inf->symfile_flags
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| SYMFILE_MAINLINE | SYMFILE_DEFER_BP_RESET),
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NULL, 0);
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if ((inf->symfile_flags & SYMFILE_NO_READ) == 0)
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set_initial_language ();
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do_cleanups (old_chain);
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/* If the target can specify a description, read it. Must do this
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after flipping to the new executable (because the target supplied
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