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[binutils-gdb] Prevent internal assembler errors if a stabs creation function builds an badly formatted input strin


https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=1181551ef0a9a7f611a3d1130d2b284280882870

commit 1181551ef0a9a7f611a3d1130d2b284280882870
Author: Nick Clifton <nickc@redhat.com>
Date:   Thu Jan 12 14:56:13 2017 +0000

    Prevent internal assembler errors if a stabs creation function builds an badly formatted input string.
    
    	* read.c (temp_ilp): New function.  Installs a temporary input
    	line pointer.
    	(restore_ilp): New function.  Restores the original input line
    	pointer.
    	* read.h (temp_ilp): Prototype.
    	(restore_ilp): Prototype.
    	* stabs.c (dot_func_p): Use bfd_boolean type.
    	(generate_asm_file): Use temp_ilp and restore_ilp.
    	(stabs_generate_asm_lineno): Likewise.
    	(stabs_generate_asm_endfunc): Likewise.

Diff:
---
 gas/ChangeLog | 13 +++++++++++++
 gas/read.c    | 44 ++++++++++++++++++++++++++++++++++++++++++++
 gas/read.h    |  2 ++
 gas/stabs.c   | 47 ++++++++++++++++++++++-------------------------
 4 files changed, 81 insertions(+), 25 deletions(-)

diff --git a/gas/ChangeLog b/gas/ChangeLog
index 580cc18..40cfce1 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,16 @@
+2017-01-12  Nick Clifton  <nickc@redhat.com>
+
+	* read.c (temp_ilp): New function.  Installs a temporary input
+	line pointer.
+	(restore_ilp): New function.  Restores the original input line
+	pointer.
+	* read.h (temp_ilp): Prototype.
+	(restore_ilp): Prototype.
+	* stabs.c (dot_func_p): Use bfd_boolean type.
+	(generate_asm_file): Use temp_ilp and restore_ilp.
+	(stabs_generate_asm_lineno): Likewise.
+	(stabs_generate_asm_endfunc): Likewise.
+
 2017-01-11  Jeremy Soller  <jackpot51@gmail.com>
 
 	* configure.tgt: Add entry for i386-redox.
diff --git a/gas/read.c b/gas/read.c
index 3669b28..4ca8b01 100644
--- a/gas/read.c
+++ b/gas/read.c
@@ -6333,3 +6333,47 @@ find_end_of_line (char *s, int mri_string)
 {
   return _find_end_of_line (s, mri_string, 0, 0);
 }
+
+static char *saved_ilp = NULL;
+static char *saved_limit;
+
+/* Use BUF as a temporary input pointer for calling other functions in this
+   file.  BUF must be a C string, so that its end can be found by strlen.
+   Also sets the buffer_limit variable (local to this file) so that buffer
+   overruns should not occur.  Saves the current input line pointer so that
+   it can be restored by calling restore_ilp().
+
+   Does not support recursion.
+
+   FIXME: This function is currently only used by stabs.c but that
+   should be extended to other files in the gas source directory.  */
+
+void
+temp_ilp (char *buf)
+{
+  gas_assert (saved_ilp == NULL);
+  gas_assert (buf != NULL);
+
+  saved_ilp = input_line_pointer;
+  saved_limit = buffer_limit;
+  /* Prevent the assert in restore_ilp from triggering if
+     the input_line_pointer has not yet been initialised.  */
+  if (saved_ilp == NULL)
+    saved_limit = saved_ilp = (char *) "";
+
+  input_line_pointer = buf;
+  buffer_limit = buf + strlen (buf);
+}
+
+/* Restore a saved input line pointer.  */
+
+void
+restore_ilp (void)
+{
+  gas_assert (saved_ilp != NULL);
+
+  input_line_pointer = saved_ilp;
+  buffer_limit = saved_limit;
+
+  saved_ilp = NULL;
+}
diff --git a/gas/read.h b/gas/read.h
index f1ccf92..e83118f 100644
--- a/gas/read.h
+++ b/gas/read.h
@@ -213,3 +213,5 @@ extern void s_xstab (int what);
 extern void s_rva (int);
 extern void s_incbin (int);
 extern void s_weakref (int);
+extern void temp_ilp (char *);
+extern void restore_ilp (void);
diff --git a/gas/stabs.c b/gas/stabs.c
index 49fc09b..f9127f0 100644
--- a/gas/stabs.c
+++ b/gas/stabs.c
@@ -46,13 +46,13 @@ static void generate_asm_file (int, const char *);
 #define STAB_STRING_SECTION_NAME ".stabstr"
 #endif
 
-/* Non-zero if we're in the middle of a .func function, in which case
+/* True if we're in the middle of a .func function, in which case
    stabs_generate_asm_lineno emits function relative line number stabs.
    Otherwise it emits line number stabs with absolute addresses.  Note that
    both cases only apply to assembler code assembled with -gstabs.  */
-static int in_dot_func_p;
+static bfd_boolean in_dot_func_p = FALSE;
 
-/* Label at start of current function if in_dot_func_p != 0.  */
+/* Label at start of current function if in_dot_func_p != FALSE.  */
 static const char *current_function_label;
 
 /*
@@ -510,7 +510,6 @@ generate_asm_file (int type, const char *file)
 {
   static char *last_file;
   static int label_count;
-  char *hold;
   char sym[30];
   char *buf;
   const char *tmp = file;
@@ -525,8 +524,6 @@ generate_asm_file (int type, const char *file)
      generate a string and then parse it again.  That lets us use the
      existing stabs hook, which expect to see a string, rather than
      inventing new ones.  */
-  hold = input_line_pointer;
-
   sprintf (sym, "%sF%d", FAKE_LABEL_NAME, label_count);
   ++label_count;
 
@@ -556,8 +553,10 @@ generate_asm_file (int type, const char *file)
 
   sprintf (bufp, "\",%d,0,0,%s\n", type, sym);
 
-  input_line_pointer = buf;
+  temp_ilp (buf);
   s_stab ('s');
+  restore_ilp ();
+
   colon (sym);
 
   if (last_file != NULL)
@@ -565,8 +564,6 @@ generate_asm_file (int type, const char *file)
   last_file = xstrdup (file);
 
   free (buf);
-
-  input_line_pointer = hold;
 }
 
 /* Generate stabs debugging information for the current line.  This is
@@ -576,7 +573,6 @@ void
 stabs_generate_asm_lineno (void)
 {
   static int label_count;
-  char *hold;
   const char *file;
   unsigned int lineno;
   char *buf;
@@ -590,8 +586,6 @@ stabs_generate_asm_lineno (void)
      existing stabs hook, which expect to see a string, rather than
      inventing new ones.  */
 
-  hold = input_line_pointer;
-
   file = as_where (&lineno);
 
   /* Don't emit sequences of stabs for the same line.  */
@@ -638,11 +632,13 @@ stabs_generate_asm_lineno (void)
       buf = XNEWVEC (char, 100);
       sprintf (buf, "%d,0,%d,%s\n", N_SLINE, lineno, sym);
     }
-  input_line_pointer = buf;
+
+  temp_ilp (buf);
   s_stab ('n');
+  restore_ilp ();
+
   colon (sym);
 
-  input_line_pointer = hold;
   outputting_stabs_line_debug = 0;
   free (buf);
 }
@@ -653,29 +649,30 @@ stabs_generate_asm_lineno (void)
 void
 stabs_generate_asm_func (const char *funcname, const char *startlabname)
 {
-  static int void_emitted_p;
-  char *hold = input_line_pointer;
+  static bfd_boolean void_emitted_p = FALSE;
   char *buf;
   unsigned int lineno;
 
   if (! void_emitted_p)
     {
-      input_line_pointer = (char *) "\"void:t1=1\",128,0,0,0";
+      temp_ilp ((char *) "\"void:t1=1\",128,0,0,0");
       s_stab ('s');
-      void_emitted_p = 1;
+      restore_ilp ();
+      void_emitted_p = TRUE;
     }
 
   as_where (&lineno);
   if (asprintf (&buf, "\"%s:F1\",%d,0,%d,%s",
 		funcname, N_FUN, lineno + 1, startlabname) == -1)
     as_fatal ("%s", xstrerror (errno));
-  input_line_pointer = buf;
+
+  temp_ilp (buf);
   s_stab ('s');
+  restore_ilp ();
   free (buf);
 
-  input_line_pointer = hold;
   current_function_label = xstrdup (startlabname);
-  in_dot_func_p = 1;
+  in_dot_func_p = TRUE;
 }
 
 /* Emit a stab to record the end of a function.  */
@@ -685,7 +682,6 @@ stabs_generate_asm_endfunc (const char *funcname ATTRIBUTE_UNUSED,
 			    const char *startlabname)
 {
   static int label_count;
-  char *hold = input_line_pointer;
   char *buf;
   char sym[30];
 
@@ -695,11 +691,12 @@ stabs_generate_asm_endfunc (const char *funcname ATTRIBUTE_UNUSED,
 
   if (asprintf (&buf, "\"\",%d,0,0,%s-%s", N_FUN, sym, startlabname) == -1)
     as_fatal ("%s", xstrerror (errno));
-  input_line_pointer = buf;
+
+  temp_ilp (buf);
   s_stab ('s');
+  restore_ilp ();
   free (buf);
 
-  input_line_pointer = hold;
-  in_dot_func_p = 0;
+  in_dot_func_p = FALSE;
   current_function_label = NULL;
 }


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