coffgrok access of u.auxent.x_sym.x_tagndx.p

u.auxent.x_sym.x_tagndx is a union.  The p field is only valid when
fix_tag is set.  This patch fixes code in coffgrok.c that accessed the
field without first checking fix_tag, and removes a whole lot of code
validating bogus pointers to prevent segfaults (which no longer
happen, I checked the referenced PR 17512 testcases).  The patch also
documents this in the fix_tag comment, makes is_sym a bitfield, and
sorts the selecter fields a little.

bfd/
	* coffcode.h (combined_entry_type): Make is_sym a bitfield.
	Sort and comment on union selectors.
	* libcoff.h: Regenerate.
binutils/
	* coffgrok.c (do_type): Make aux a combined_entry_type.  Test
	fix_tag before accessing u.auxent.x_sym.x_tagndx.p.  Remove
	now unnecessary pointer bounds checking.

1 files changed, 15 insertions, 15 deletions

diff --git a/bfd/coffcode.h b/bfd/coffcode.h
index bf55d83..d4a2a5c 100644
--- a/bfd/coffcode.h
+++ b/bfd/coffcode.h
@@ -294,27 +294,30 @@ CODE_FRAGMENT
 .typedef struct coff_ptr_struct
 .{
 .  {* Remembers the offset from the first symbol in the file for
-.     this symbol. Generated by coff_renumber_symbols.  *}
+.     this symbol.  Generated by coff_renumber_symbols.  *}
 .  unsigned int offset;
 .
-.  {* Should the value of this symbol be renumbered.  Used for
-.     XCOFF C_BSTAT symbols.  Set by coff_slurp_symbol_table.  *}
-.  unsigned int fix_value : 1;
+.  {* Selects between the elements of the union below.  *}
+.  unsigned int is_sym : 1;
 .
-.  {* Should the tag field of this symbol be renumbered.
-.     Created by coff_pointerize_aux.  *}
+.  {* Selects between the elements of the x_sym.x_tagndx union.  If set,
+.     p is valid and the field will be renumbered.  *}
 .  unsigned int fix_tag : 1;
 .
-.  {* Should the endidx field of this symbol be renumbered.
-.     Created by coff_pointerize_aux.  *}
+.  {* Selects between the elements of the x_sym.x_fcnary.x_fcn.x_endndx
+.     union.  If set, p is valid and the field will be renumbered.  *}
 .  unsigned int fix_end : 1;
 .
-.  {* Should the x_csect.x_scnlen field be renumbered.
-.     Created by coff_pointerize_aux.  *}
+.  {* Selects between the elements of the x_csect.x_scnlen union.  If set,
+.     p is valid and the field will be renumbered.  *}
 .  unsigned int fix_scnlen : 1;
 .
-.  {* Fix up an XCOFF C_BINCL/C_EINCL symbol.  The value is the
-.     index into the line number entries.  Set by coff_slurp_symbol_table.  *}
+.  {* If set, u.syment.n_value contains a pointer to a symbol.  The final
+.     value will be the offset field.  Used for XCOFF C_BSTAT symbols.  *}
+.  unsigned int fix_value : 1;
+.
+.  {* If set, u.syment.n_value is an index into the line number entries.
+.     Used for XCOFF C_BINCL/C_EINCL symbols.  *}
 .  unsigned int fix_line : 1;
 .
 .  {* The container for the symbol structure as read and translated
@@ -325,9 +328,6 @@ CODE_FRAGMENT
 .    struct internal_syment syment;
 .  } u;
 .
-. {* Selector for the union above.  *}
-. bool is_sym;
-.
 . {* An extra pointer which can used by format based on COFF (like XCOFF)
 .    to provide extra information to their backend.  *}
 . void *extrap;