som: buffer overflow writing strings

Code in som_write_symbol_strings neglected to allow for padding, which
can result in a buffer overflow.  It also used xrealloc, which we're
not supposed to use in libbfd because libbfd isn't supposed to call
exit.  Also a realloc is perhaps not a good idea when none of the
buffer contents are needed, so replace with free, bfd_malloc.  There
were three copies of the string handling code, so rather than fix them
all I've extracted them to a function.  This necessitated making one
of the fields in struct som_symbol unsigned.

	* som.c (add_string): New function.
	(som_write_space_strings, som_write_symbol_strings): Use it.
	* som.h (som_symbol_type <stringtab_offset>): Make unsigned.

1 files changed, 1 insertions, 1 deletions

diff --git a/bfd/som.h b/bfd/som.h
index 8152cfc..a6f91a0 100644
--- a/bfd/som.h
+++ b/bfd/som.h
@@ -81,7 +81,7 @@ typedef struct som_symbol
 
   /* During object file writing, the offset of the name of this symbol
      in the SOM string table.  */
-  int stringtab_offset;
+  unsigned int stringtab_offset;
 }
 som_symbol_type;