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* bfd_close_all_done bug and bfd_last_cache
@ 2023-08-21 10:42 Alan Modra
  0 siblings, 0 replies; only message in thread
From: Alan Modra @ 2023-08-21 10:42 UTC (permalink / raw)
  To: binutils

bfd_close ought to always call iovec->bclose so that cache_bclose is
called.  If not, bfd_last_cache will be left pointing at freed memory.
This bug was found by oss-fuzz with the trigger being an old bug in
the ia64-vms support.  Given a file of the "wrong" size,
elf64_vms_close_and_cleanup attempted to extend it, leading to an
error since the file was opened read-only by nm.  nm bad_file bad_file
then hit the use-after-free when opening the second file.

commit 8219cab3f8 fixed multiple bugs of this type in bfd_close and
bfd_close_all_done, but didn't go quite far enough.

	* elf64-ia64-vms.c (elf64_vms_close_and_cleanup): Don't
	attempt to extend read-only files.
	* opncls.c (bfd_close_all_done): Always call _close_and_cleanup.

An old bug in the ia64-vms support can be used to tickle another bug
in bfd_close_all_done.  If _close_and_cleanup returns an error,

diff --git a/bfd/elf64-ia64-vms.c b/bfd/elf64-ia64-vms.c
index f8e9922fc4a..ab1f18b8d81 100644
--- a/bfd/elf64-ia64-vms.c
+++ b/bfd/elf64-ia64-vms.c
@@ -4713,7 +4713,8 @@ static bool
 elf64_vms_close_and_cleanup (bfd *abfd)
   bool ret = true;
-  if (bfd_get_format (abfd) == bfd_object)
+  if (bfd_get_format (abfd) == bfd_object
+      && bfd_write_p (abfd))
       long isize;
diff --git a/bfd/opncls.c b/bfd/opncls.c
index 56a90046b1a..741d20e81da 100644
--- a/bfd/opncls.c
+++ b/bfd/opncls.c
@@ -920,13 +920,11 @@ bfd_close_all_done (bfd *abfd)
   bool ret = BFD_SEND (abfd, _close_and_cleanup, (abfd));
-  if (ret && abfd->iovec != NULL)
-    {
-      ret = abfd->iovec->bclose (abfd) == 0;
+  if (abfd->iovec != NULL)
+    ret &= abfd->iovec->bclose (abfd) == 0;
-      if (ret)
-	_maybe_make_executable (abfd);
-    }
+  if (ret)
+    _maybe_make_executable (abfd);
   _bfd_delete_bfd (abfd);
   free (_bfd_error_buf);

Alan Modra
Australia Development Lab, IBM

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