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The fix for bug 1012343:
https://bugzilla.redhat.com/show_bug.cgi?id=1012343

It results in an unterminated string being passed as a mode to fopen which results in the potential use of uninitialized data.

--- a/misc/mntent_r.c
+++ b/misc/mntent_r.c
@@ -40,10 +40,10 @@
 __setmntent (const char *file, const char *mode)
 {
   /* Extend the mode parameter with "c" to disable cancellation in the
-     I/O functions.  */
+     I/O functions and "e" to set FD_CLOEXEC.  */
   size_t modelen = strlen (mode);
   char newmode[modelen + 2];
-  memcpy (mempcpy (newmode, mode, modelen), "c", 2);
+  memcpy (mempcpy (newmode, mode, modelen), "ce", 2);
   FILE *result = fopen (file, newmode);

   if (result != NULL)

The newmode should be size modelen + 3 and the memcpy should copy 3 bytes.

An audit revealed that also needed are cancellation fixes for:

getttyent.c
files-netgrp.c
res_hconf.c

So we must fix those up also.

The fix for bug 952422 fixed the cancellation issue with getsysstats.c already.

Fist reported here: https://blogs.oracle.com/wim/entry/oracle_linux_6_update_9

(Via bug 1012343 comment 21.)

*** Bug 1437111 has been marked as a duplicate of this bug. ***

Fixes complete and undergoing internal review.

(In reply to Carlos O'Donell from comment #0)
> Contains a defect that results in a 1-byte buffer overflow.

This statement is incorrect. It results in an unterminated string being passed as a mode to fopen which results in the potential use of uninitialized data.

*** Bug 1394704 has been marked as a duplicate of this bug. ***

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHSA-2018:1879