diff --git a/backport-fix-missing-mutex-unlock.patch b/backport-fix-missing-mutex-unlock.patch
new file mode 100644
index 0000000000000000000000000000000000000000..2d45b09b8097d03a1847d0057a9e7faf9a36539a
--- /dev/null
+++ b/backport-fix-missing-mutex-unlock.patch
@@ -0,0 +1,43 @@
+From ee24a31ae1735c03d58576d2dc43274735c8fbef Mon Sep 17 00:00:00 2001
+From: ycaibb <ycaibb@gmail.com>
+Date: Fri, 10 Sep 2021 19:44:54 +0800
+Subject: [PATCH] fix missing mutex unlock
+
+Fixes a missing mutex unlock on an out of memory error
+in ltc_ecc_fp_save_state().
+
+Originates from: https://github.com/OP-TEE/optee_os/commit/4af447d4084e293800d4e463d65003c016b91f29
+
+Fixes #571
+
+Comment by sj:
+This patch version slightly deviates from the original patch to OP-TEE
+since we don't call `XFREE(NULL)` as there exist implementations of
+`free()` that don't support it.
+
+Signed-off-by: Ryan Cai <ycaibb@gmail.com>
+Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
+Modified-by: Steffen Jaeckel <s@jaeckel.eu>
+---
+ src/math/fp/ltc_ecc_fp_mulmod.c | 4 +++-
+ 1 file changed, 3 insertions(+), 1 deletion(-)
+
+diff --git a/src/math/fp/ltc_ecc_fp_mulmod.c b/src/math/fp/ltc_ecc_fp_mulmod.c
+index 5827bf3b..9be2ebf1 100644
+--- a/src/math/fp/ltc_ecc_fp_mulmod.c
++++ b/src/math/fp/ltc_ecc_fp_mulmod.c
+@@ -1429,8 +1429,10 @@ int ltc_ecc_fp_save_state(unsigned char **out, unsigned long *outlen)
+     * and the mu INTEGER
+     */
+    cache_entry = XCALLOC(FP_ENTRIES*(2*(1U<<FP_LUT)+4)+3, sizeof(ltc_asn1_list));
+-   if (cache_entry == NULL)
++   if (cache_entry == NULL) {
++      LTC_MUTEX_UNLOCK(&ltc_ecc_fp_lock);
+       return CRYPT_MEM;
++   }
+    j = 1;   /* handle the zero'th element later */
+ 
+    LTC_SET_ASN1(cache_entry, j++, LTC_ASN1_SHORT_INTEGER, &fp_entries, 1);
+-- 
+2.33.0
+
diff --git a/libtomcrypt.spec b/libtomcrypt.spec
index 2d4056d9ed759602f49096447d3f72b360e4d9ee..2aa4466586b99030cacb4ccff14a06d1864eb482 100644
--- a/libtomcrypt.spec
+++ b/libtomcrypt.spec
@@ -1,11 +1,12 @@
 Name:            libtomcrypt
 Version:         1.18.2
-Release:         5
+Release:         6
 Summary:         A comprehensive, portable cryptographic toolkit
 License:         Public Domain or WTFPL
 URL:             http://www.libtom.net/
 Source0:         https://github.com/libtom/%{name}/archive/v%{version}/%{name}-%{version}.tar.gz
 Patch0:          CVE-2019-17362.patch
+Patch1:          backport-fix-missing-mutex-unlock.patch
 BuildRequires:   libtommath-devel libtool
 
 %description
@@ -53,6 +54,9 @@ make test
 %{_libdir}/pkgconfig/*.pc
 
 %changelog
+* Tue Jul 2 2024 yixiangzhike <yixiangzhike007@163.com> - 1.18.2-6
+- backport upstream patch to fix missing mutex unlock
+
 * Wed Apr 13 2022 yixiangzhike <yixiangzhike007@163.com> - 1.18.2-5
 - enable test suite in check