diff --git a/0001-mount.cifs-fix-tests-for-strtoul-success.patch b/0001-mount.cifs-fix-tests-for-strtoul-success.patch
new file mode 100644
index 0000000..b074108
--- /dev/null
+++ b/0001-mount.cifs-fix-tests-for-strtoul-success.patch
@@ -0,0 +1,83 @@
+From f6384b4fe1ffdeebee3e9d73dd533a4fbf83b6d8 Mon Sep 17 00:00:00 2001
+From: Jeff Layton <jlayton@samba.org>
+Date: Thu, 23 Feb 2012 10:42:09 -0500
+Subject: [PATCH] mount.cifs: fix tests for strtoul success
+
+The current test just looks to see if errno was 0 after the conversion
+but we need to do a bit more. According to the strtoul manpage:
+
+    If there were no digits at all, strtoul() stores the original value
+    of nptr in *endptr (and returns 0).
+
+So, if you pass in a string of letters, strtoul will return 0, but
+won't actually have converted anything. Luckily, in most cases, /bin/mount
+papers over this bug by doing uid/gid conversions itself before calling
+mount.cifs.
+
+Fix this by also checking to ensure that strtoul() converted the entire
+string in addition to checking that it didn't set errno. While we're at
+it, fix the test in backupuid/backupgid options as well which don't
+currently check whether errno got set.
+
+Reported-by: Kyle Squizzato <ksquizza@redhat.com>
+Signed-off-by: Jeff Layton <jlayton@samba.org>
+---
+ mount.cifs.c |   12 +++++++-----
+ 1 files changed, 7 insertions(+), 5 deletions(-)
+
+diff --git a/mount.cifs.c b/mount.cifs.c
+index a46a22c..824cd3a 100644
+--- a/mount.cifs.c
++++ b/mount.cifs.c
+@@ -1032,7 +1032,7 @@ parse_options(const char *data, struct parsed_mount_info *parsed_info)
+ 			got_uid = 1;
+ 			errno = 0;
+ 			uid = strtoul(value, &ep, 10);
+-			if (errno == 0)
++			if (errno == 0 && *ep == '\0')
+ 				goto nocopy;
+ 
+ 			pw = getpwnam(value);
+@@ -1051,7 +1051,7 @@ parse_options(const char *data, struct parsed_mount_info *parsed_info)
+ 			got_cruid = 1;
+ 			errno = 0;
+ 			cruid = strtoul(value, &ep, 10);
+-			if (errno == 0)
++			if (errno == 0 && *ep == '\0')
+ 				goto nocopy;
+ 
+ 			pw = getpwnam(value);
+@@ -1069,7 +1069,7 @@ parse_options(const char *data, struct parsed_mount_info *parsed_info)
+ 			got_gid = 1;
+ 			errno = 0;
+ 			gid = strtoul(value, &ep, 10);
+-			if (errno == 0)
++			if (errno == 0 && *ep == '\0')
+ 				goto nocopy;
+ 
+ 			gr = getgrnam(value);
+@@ -1175,8 +1175,9 @@ parse_options(const char *data, struct parsed_mount_info *parsed_info)
+ 				goto nocopy;
+ 
+ 			got_bkupuid = 1;
++			errno = 0;
+ 			bkupuid = strtoul(value, &ep, 10);
+-			if (!strlen(ep))
++			if (errno == 0 && *ep == '\0')
+ 				goto nocopy;
+ 
+ 			pw = getpwnam(value);
+@@ -1193,8 +1194,9 @@ parse_options(const char *data, struct parsed_mount_info *parsed_info)
+ 				goto nocopy;
+ 
+ 			got_bkupgid = 1;
++			errno = 0;
+ 			bkupgid = strtoul(value, &ep, 10);
+-			if (!strlen(ep))
++			if (errno == 0 && *ep == '\0')
+ 				goto nocopy;
+ 
+ 			gr = getgrnam(value);
+-- 
+1.7.7.6
+
diff --git a/cifs-utils.spec b/cifs-utils.spec
index 61aafb3..60b6e8f 100644
--- a/cifs-utils.spec
+++ b/cifs-utils.spec
@@ -3,7 +3,7 @@
 
 Name:           cifs-utils
 Version:        5.3
-Release:        3%{pre_release}%{?dist}
+Release:        4%{pre_release}%{?dist}
 Summary:        Utilities for mounting and managing CIFS mounts
 
 Group:          System Environment/Daemons
@@ -12,6 +12,7 @@ URL:            http://linux-cifs.samba.org/cifs-utils/
 BuildRoot:      %{_tmppath}/%{name}-%{version}%{pre_release}-%{release}-root-%(%{__id_u} -n)
 
 Source0:        ftp://ftp.samba.org/pub/linux-cifs/cifs-utils/%{name}-%{version}%{pre_release}.tar.bz2
+Patch0:         0001-mount.cifs-fix-tests-for-strtoul-success.patch
 
 BuildRequires:  libcap-ng-devel libtalloc-devel krb5-devel keyutils-libs-devel autoconf automake samba-winbind-devel
 Requires:       keyutils
@@ -26,6 +27,7 @@ file system.
 
 %prep
 %setup -q -n %{name}-%{version}%{pre_release}
+%patch0 -p1
 
 %build
 %configure --prefix=/usr
@@ -60,6 +62,9 @@ rm -rf %{buildroot}
 %config(noreplace) %{_sysconfdir}/request-key.d/cifs.spnego.conf
 
 %changelog
+* Mon Mar 19 2012 Jeff Layton <jlayton@redhat.com> 5.3-4
+- fix tests for strtoul success (bz# 800621)
+
 * Wed Feb 08 2012 Jeff Layton <jlayton@redhat.com> 5.3-3
 - revert mount.cifs move. It's unnecessary at this point.