diff --git a/glibc-iconvconfig-corruption.patch b/glibc-iconvconfig-corruption.patch
new file mode 100644
index 0000000..4b18758
--- /dev/null
+++ b/glibc-iconvconfig-corruption.patch
@@ -0,0 +1,107 @@
+Emergency patch from libc-alpha.
+
+From: Siddhesh Poyarekar <siddhesh@sourceware.org>
+Subject: [PATCH v2] iconvconfig: Fix multiple issues
+To: libc-alpha@sourceware.org
+Cc: schwab@linux-m68k.org, fweimer@redhat.com
+Date: Fri, 25 Jun 2021 14:31:28 +0530
+Message-Id: <20210625090128.316837-1-siddhesh@sourceware.org>
+
+It was noticed on big-endian systems that msgfmt would fail with the
+following error:
+
+msgfmt: gconv_builtin.c:70: __gconv_get_builtin_trans: Assertion `cnt < sizeof (map) / sizeof (map[0])' failed.
+Aborted (core dumped)
+
+This is only seen on installed systems because it was due to a
+corrupted gconv-modules.cache.  iconvconfig had the following issues
+(it was specifically freeing fulldir that caused this issue, but other
+cleanups are also needed) that this patch fixes.
+
+- Add prefix only if dir starts with '/'
+- Use asprintf instead of mempcpy so that the directory string is NULL
+  terminated
+- Make a copy of the directory reference in new_module so that fulldir
+  can be freed within the same scope in handle_dir.
+---
+ iconv/Makefile      |  2 +-
+ iconv/iconvconfig.c | 24 +++++++++---------------
+ 2 files changed, 10 insertions(+), 16 deletions(-)
+
+diff --git a/iconv/Makefile b/iconv/Makefile
+index a9b267c851..07d77c9eca 100644
+--- a/iconv/Makefile
++++ b/iconv/Makefile
+@@ -33,7 +33,7 @@ vpath %.c ../locale/programs ../intl
+ iconv_prog-modules = iconv_charmap charmap charmap-dir linereader \
+ 		     dummy-repertoire simple-hash xstrdup xmalloc \
+ 		     record-status
+-iconvconfig-modules = strtab xmalloc hash-string
++iconvconfig-modules = strtab xmalloc xasprintf xstrdup hash-string
+ extra-objs	   = $(iconv_prog-modules:=.o) $(iconvconfig-modules:=.o)
+ CFLAGS-iconv_prog.c += -I../locale/programs
+ CFLAGS-iconv_charmap.c += -I../locale/programs
+diff --git a/iconv/iconvconfig.c b/iconv/iconvconfig.c
+index e69334d71c..783b2bbdbb 100644
+--- a/iconv/iconvconfig.c
++++ b/iconv/iconvconfig.c
+@@ -250,6 +250,7 @@ static const char gconv_module_ext[] = MODULE_EXT;
+ 
+ 
+ #include <programs/xmalloc.h>
++#include <programs/xasprintf.h>
+ 
+ 
+ /* C string table handling.  */
+@@ -519,11 +520,12 @@ module_compare (const void *p1, const void *p2)
+ /* Create new module record.  */
+ static void
+ new_module (const char *fromname, size_t fromlen, const char *toname,
+-	    size_t tolen, const char *directory,
++	    size_t tolen, const char *dir_in,
+ 	    const char *filename, size_t filelen, int cost, size_t need_ext)
+ {
+   struct module *new_module;
+-  size_t dirlen = strlen (directory) + 1;
++  size_t dirlen = strlen (dir_in) + 1;
++  const char *directory = xstrdup (dir_in);
+   char *tmp;
+   void **inserted;
+ 
+@@ -654,20 +656,10 @@ handle_dir (const char *dir)
+   size_t dirlen = strlen (dir);
+   bool found = false;
+ 
+-  /* Add the prefix before sending it off to the parser.  */
+-  char *fulldir = xmalloc (prefix_len + dirlen + 2);
+-  char *cp = mempcpy (mempcpy (fulldir, prefix, prefix_len), dir, dirlen);
++  char *fulldir = xasprintf ("%s%s%s", dir[0] == '/' ? prefix : "",
++			     dir, dir[dirlen - 1] != '/' ? "/" : "");
+ 
+-  if (dir[dirlen - 1] != '/')
+-    {
+-      *cp++ = '/';
+-      *cp = '\0';
+-      dirlen++;
+-    }
+-
+-  found = gconv_parseconfdir (fulldir, dirlen + prefix_len);
+-
+-  free (fulldir);
++  found = gconv_parseconfdir (fulldir, strlen (fulldir));
+ 
+   if (!found)
+     {
+@@ -679,6 +671,8 @@ handle_dir (const char *dir)
+ 	     "configuration files with names ending in .conf.");
+     }
+ 
++  free (fulldir);
++
+   return found ? 0 : 1;
+ }
+ 
+-- 
+
+2.31.1
+
diff --git a/glibc.spec b/glibc.spec
index 42056ed..7f0ff38 100644
--- a/glibc.spec
+++ b/glibc.spec
@@ -111,7 +111,7 @@
 Summary: The GNU libc libraries
 Name: glibc
 Version: %{glibcversion}
-Release: 28%{?dist}
+Release: 29%{?dist}
 
 # In general, GPLv2+ is used by programs, LGPLv2+ is used for
 # libraries.
@@ -195,6 +195,7 @@ Patch35: glibc-nosymlink-2.patch
 Patch36: glibc-nosymlink-3.patch
 Patch37: glibc-nosymlink-4.patch
 Patch38: glibc-libthread_db-dynsym.patch
+Patch39: glibc-iconvconfig-corruption.patch
 
 ##############################################################################
 # Continued list of core "glibc" package information:
@@ -2212,6 +2213,9 @@ fi
 %files -f compat-libpthread-nonshared.filelist -n compat-libpthread-nonshared
 
 %changelog
+* Sun Jun 27 2021 Florian Weimer <fweimer@redhat.com> - 2.33.9000-29
+- Apply emergency patch to fix iconvconfig corruption
+
 * Sun Jun 27 2021 Florian Weimer <fweimer@redhat.com> - 2.33.9000-28
 - Adjust glibc.req so that egrep does not cause eu-readelf to fail