Fix an off by one error while calling mbrtowc()

Resolves: #2115206

bash-5.1-mbrtowc.patch

@@ -0,0 +1,12 @@
+diff --git a/subst.c b/subst.c
+--- a/subst.c
++++ b/subst.c
+@@ -6240,7 +6240,7 @@ read_comsub (fd, quoted, flags, rflag)
+ 	  /* read a multibyte character from buf */
+ 	  /* punt on the hard case for now */
+ 	  memset (&ps, '\0', sizeof (mbstate_t));
+-	  mblen = mbrtowc (&wc, bufp-1, bufn+1, &ps);
++	  mblen = mbrtowc (&wc, bufp-1, bufn, &ps);
+ 	  if (MB_INVALIDCH (mblen) || mblen == 0 || mblen == 1)
+ 	    istring[istring_index++] = c;
+ 	  else

bash.spec

@@ -6,7 +6,7 @@
 Version: %{baseversion}%{patchleveltag}
 Name: bash
 Summary: The GNU Bourne Again shell
-Release: 4%{?dist}
+Release: 5%{?dist}
 License: GPLv3+
 Url: https://www.gnu.org/software/bash
 Source0: https://ftp.gnu.org/gnu/bash/bash-%{baseversion}.tar.gz
@@ -87,6 +87,9 @@ Patch127: bash-4.4-no-loadable-builtins.patch
 # This option is undocumented in upstream and is documented by this patch
 Patch128: bash-5.0-syslog-history.patch
 
+# 2115206 - String matching behaves differently on aarch64
+Patch129: bash-5.1-mbrtowc.patch
+
 BuildRequires:  gcc
 BuildRequires: texinfo bison
 BuildRequires: ncurses-devel
@@ -318,6 +321,10 @@ end
 %{_libdir}/pkgconfig/%{name}.pc
 
 %changelog
+* Mon Aug 08 2022 Siteshwar Vashisht <svashisht@redhat.com> - 5.1.8-5
+- Fix an off by one error while calling mbrtowc()
+  Resolves: #2115206
+
 * Fri Nov 05 2021 Siteshwar Vashisht <svashisht@redhat.com> - 5.1.8-4
 - Fix runtime option to enable history logging to syslog
   Resolves: #2020519