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author | Sandra Loosemore <sandra@codesourcery.com> | 2016-10-26 12:12:01 -0500 |
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committer | Pedro Alves <palves@redhat.com> | 2016-10-26 16:47:46 +0100 |
commit | ecf45d2cc7667ed4692d07e52fc77a2c9a8adf1c (patch) | |
tree | abc757e04ab221b35d3d0db5afba7f9f82da645a /gdb/infrun.c | |
parent | b15cc25cbe7c13e450f77b4a309223b9b3da3936 (diff) | |
download | gdb-ecf45d2cc7667ed4692d07e52fc77a2c9a8adf1c.zip gdb-ecf45d2cc7667ed4692d07e52fc77a2c9a8adf1c.tar.gz gdb-ecf45d2cc7667ed4692d07e52fc77a2c9a8adf1c.tar.bz2 |
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.
Diffstat (limited to 'gdb/infrun.c')
-rw-r--r-- | gdb/infrun.c | 48 |
1 files changed, 23 insertions, 25 deletions
diff --git a/gdb/infrun.c b/gdb/infrun.c index 5e62472..b10aa03 100644 --- a/gdb/infrun.c +++ b/gdb/infrun.c @@ -1077,15 +1077,17 @@ show_follow_exec_mode_string (struct ui_file *file, int from_tty, fprintf_filtered (file, _("Follow exec mode is \"%s\".\n"), value); } -/* EXECD_PATHNAME is assumed to be non-NULL. */ +/* EXEC_FILE_TARGET is assumed to be non-NULL. */ static void -follow_exec (ptid_t ptid, char *execd_pathname) +follow_exec (ptid_t ptid, char *exec_file_target) { struct thread_info *th, *tmp; struct inferior *inf = current_inferior (); int pid = ptid_get_pid (ptid); ptid_t process_ptid; + char *exec_file_host; + struct cleanup *old_chain; /* This is an exec event that we actually wish to pay attention to. Refresh our symbol table to the newly exec'd program, remove any @@ -1155,7 +1157,7 @@ follow_exec (ptid_t ptid, char *execd_pathname) process_ptid = pid_to_ptid (pid); printf_unfiltered (_("%s is executing new program: %s\n"), target_pid_to_str (process_ptid), - execd_pathname); + exec_file_target); /* We've followed the inferior through an exec. Therefore, the inferior has essentially been killed & reborn. */ @@ -1164,14 +1166,17 @@ follow_exec (ptid_t ptid, char *execd_pathname) breakpoint_init_inferior (inf_execd); - if (*gdb_sysroot != '\0') - { - char *name = exec_file_find (execd_pathname, NULL); + exec_file_host = exec_file_find (exec_file_target, NULL); + old_chain = make_cleanup (xfree, exec_file_host); - execd_pathname = (char *) alloca (strlen (name) + 1); - strcpy (execd_pathname, name); - xfree (name); - } + /* If we were unable to map the executable target pathname onto a host + pathname, tell the user that. Otherwise GDB's subsequent behavior + is confusing. Maybe it would even be better to stop at this point + so that the user can specify a file manually before continuing. */ + if (exec_file_host == NULL) + warning (_("Could not load symbols for executable %s.\n" + "Do you need \"set sysroot\"?"), + exec_file_target); /* Reset the shared library package. This ensures that we get a shlib event when the child reaches "_start", at which point the @@ -1193,7 +1198,7 @@ follow_exec (ptid_t ptid, char *execd_pathname) inf = add_inferior_with_spaces (); inf->pid = pid; - target_follow_exec (inf, execd_pathname); + target_follow_exec (inf, exec_file_target); set_current_inferior (inf); set_current_program_space (inf->pspace); @@ -1212,21 +1217,14 @@ follow_exec (ptid_t ptid, char *execd_pathname) gdb_assert (current_program_space == inf->pspace); - /* That a.out is now the one to use. */ - exec_file_attach (execd_pathname, 0); + /* Attempt to open the exec file. SYMFILE_DEFER_BP_RESET is used + because the proper displacement for a PIE (Position Independent + Executable) main symbol file will only be computed by + solib_create_inferior_hook below. breakpoint_re_set would fail + to insert the breakpoints with the zero displacement. */ + try_open_exec_file (exec_file_host, inf, SYMFILE_DEFER_BP_RESET); - /* SYMFILE_DEFER_BP_RESET is used as the proper displacement for PIE - (Position Independent Executable) main symbol file will get applied by - solib_create_inferior_hook below. breakpoint_re_set would fail to insert - the breakpoints with the zero displacement. */ - - symbol_file_add (execd_pathname, - (inf->symfile_flags - | SYMFILE_MAINLINE | SYMFILE_DEFER_BP_RESET), - NULL, 0); - - if ((inf->symfile_flags & SYMFILE_NO_READ) == 0) - set_initial_language (); + do_cleanups (old_chain); /* If the target can specify a description, read it. Must do this after flipping to the new executable (because the target supplied |