PR24236, Heap buffer overflow in _bfd_archive_64_bit_slurp_armap

Message ID 20190220011920.GB16787@bubble.grove.modra.org
State New
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Series
  • PR24236, Heap buffer overflow in _bfd_archive_64_bit_slurp_armap
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Commit Message

Alan Modra Feb. 20, 2019, 1:19 a.m.
PR 24236
	* archive64.c (_bfd_archive_64_bit_slurp_armap): Move code adding
	sentinel NUL to string buffer nearer to loop where it is used.
	Don't go past sentinel when scanning strings, and don't write
	NUL again.
	* archive.c (do_slurp_coff_armap): Simplify string handling to
	archive64.c style.


-- 
Alan Modra
Australia Development Lab, IBM

Patch

diff --git a/bfd/archive64.c b/bfd/archive64.c
index 312bf823eb..42f6ed92f0 100644
--- a/bfd/archive64.c
+++ b/bfd/archive64.c
@@ -100,8 +100,6 @@  _bfd_archive_64_bit_slurp_armap (bfd *abfd)
     return FALSE;
   carsyms = ardata->symdefs;
   stringbase = ((char *) ardata->symdefs) + carsym_size;
-  stringbase[stringsize] = 0;
-  stringend = stringbase + stringsize;
 
   raw_armap = (bfd_byte *) bfd_alloc (abfd, ptrsize);
   if (raw_armap == NULL)
@@ -115,15 +113,17 @@  _bfd_archive_64_bit_slurp_armap (bfd *abfd)
       goto release_raw_armap;
     }
 
+  stringend = stringbase + stringsize;
+  *stringend = 0;
   for (i = 0; i < nsymz; i++)
     {
       carsyms->file_offset = bfd_getb64 (raw_armap + i * 8);
       carsyms->name = stringbase;
-      if (stringbase < stringend)
-	stringbase += strlen (stringbase) + 1;
+      stringbase += strlen (stringbase);
+      if (stringbase != stringend)
+	++stringbase;
       ++carsyms;
     }
-  *stringbase = '\0';
 
   ardata->symdef_count = nsymz;
   ardata->first_file_filepos = bfd_tell (abfd);
diff --git a/bfd/archive.c b/bfd/archive.c
index d2d9b728d8..68a92a3e36 100644
--- a/bfd/archive.c
+++ b/bfd/archive.c
@@ -1012,6 +1012,7 @@  do_slurp_coff_armap (bfd *abfd)
   int *raw_armap, *rawptr;
   struct artdata *ardata = bfd_ardata (abfd);
   char *stringbase;
+  char *stringend;
   bfd_size_type stringsize;
   bfd_size_type parsed_size;
   carsym *carsyms;
@@ -1071,22 +1072,18 @@  do_slurp_coff_armap (bfd *abfd)
     }
 
   /* OK, build the carsyms.  */
-  for (i = 0; i < nsymz && stringsize > 0; i++)
+  stringend = stringbase + stringsize;
+  *stringend = 0;
+  for (i = 0; i < nsymz; i++)
     {
-      bfd_size_type len;
-
       rawptr = raw_armap + i;
       carsyms->file_offset = swap ((bfd_byte *) rawptr);
       carsyms->name = stringbase;
-      /* PR 17512: file: 4a1d50c1.  */
-      len = strnlen (stringbase, stringsize);
-      if (len < stringsize)
-	len ++;
-      stringbase += len;
-      stringsize -= len;
+      stringbase += strlen (stringbase);
+      if (stringbase != stringend)
+	++stringbase;
       carsyms++;
     }
-  *stringbase = 0;
 
   ardata->symdef_count = nsymz;
   ardata->first_file_filepos = bfd_tell (abfd);