diff mbox

Fix null dereference SEGV during 'maint print arch' caused by the disassembler-options patch

Message ID eeb1de35-bcd0-8cec-2fbd-9c2799953861@vnet.ibm.com
State New, archived
Headers

Commit Message

Peter Bergner March 6, 2017, 7:50 p.m. UTC 
  The change of disassembler_options from a char * to a char **, led to a NULL
pointer reference when we do a "maint print arch" command on architectures
that do not support "set/show disassembler-options ..." (eg, x86).
The following patch adds a pstring_ptr() routine which can dump the
current set of disassembler options without segv'ing.  Fixing that exposed
a similar issue with the valid_disassembler_options field.  I solved that
but dumping the address of the valid_disassembler_options struct rather
than its "name" field.

Ok for trunk?

Peter

	* gdbarch.sh (pstring_ptr): New static function.
	(gdbarch_disassembler_options): Use it.
	(gdbarch_verify_disassembler_options): Print valid_disassembler_options,
	not valid_disassembler_option->name.
	* gdbarch.c: Regenerate.
diff mbox

Patch

diff --git a/gdb/gdbarch.sh b/gdb/gdbarch.sh
index 6902e0e..39b1f94 100755
--- a/gdb/gdbarch.sh
+++ b/gdb/gdbarch.sh
@@ -1164,8 +1164,8 @@  m:const char *:gnu_triplet_regexp:void:::default_gnu_triplet_regexp::0
 m:int:addressable_memory_unit_size:void:::default_addressable_memory_unit_size::0
 
 # Functions for allowing a target to modify its disassembler options.
-v:char **:disassembler_options:::0:0::0:pstring (*gdbarch->disassembler_options)
-v:const disasm_options_t *:valid_disassembler_options:::0:0::0:host_address_to_string (gdbarch->valid_disassembler_options->name)
+v:char **:disassembler_options:::0:0::0:pstring_ptr (gdbarch->disassembler_options)
+v:const disasm_options_t *:valid_disassembler_options:::0:0::0:host_address_to_string (gdbarch->valid_disassembler_options)
 
 EOF
 }
@@ -1678,6 +1678,14 @@  pstring (const char *string)
   return string;
 }
 
+static char *
+pstring_ptr (char **string)
+{
+  if (string == NULL || *string == NULL)
+    return "(null)";
+  return *string;
+}
+
 /* Helper function to print a list of strings, represented as "const
    char *const *".  The list is printed comma-separated.  */
 
diff --git a/gdb/gdbarch.c b/gdb/gdbarch.c
index f52cf5d..87eafb2 100644
--- a/gdb/gdbarch.c
+++ b/gdb/gdbarch.c
@@ -84,6 +84,14 @@  pstring (const char *string)
   return string;
 }
 
+static char *
+pstring_ptr (char **string)
+{
+  if (string == NULL || *string == NULL)
+    return "(null)";
+  return *string;
+}
+
 /* Helper function to print a list of strings, represented as "const
    char *const *".  The list is printed comma-separated.  */
 
@@ -880,7 +888,7 @@  gdbarch_dump (struct gdbarch *gdbarch, struct ui_file *file)
                       core_addr_to_string_nz (gdbarch->deprecated_function_start_offset));
   fprintf_unfiltered (file,
                       "gdbarch_dump: disassembler_options = %s\n",
-                      pstring (*gdbarch->disassembler_options));
+                      pstring_ptr (gdbarch->disassembler_options));
   fprintf_unfiltered (file,
                       "gdbarch_dump: gdbarch_displaced_step_copy_insn_p() = %d\n",
                       gdbarch_displaced_step_copy_insn_p (gdbarch));
@@ -1429,7 +1437,7 @@  gdbarch_dump (struct gdbarch *gdbarch, struct ui_file *file)
                       host_address_to_string (gdbarch->unwind_sp));
   fprintf_unfiltered (file,
                       "gdbarch_dump: valid_disassembler_options = %s\n",
-                      host_address_to_string (gdbarch->valid_disassembler_options->name));
+                      host_address_to_string (gdbarch->valid_disassembler_options));
   fprintf_unfiltered (file,
                       "gdbarch_dump: value_from_register = <%s>\n",
                       host_address_to_string (gdbarch->value_from_register));