From: Eugene Syromiatnikov <esyr@openssl.org>
Date: Sun, 22 Mar 2026 01:16:27 +0000 (+0100)
Subject: crypto/idea/i_ofb64.c: mask the num value after negativity check
X-Git-Tag: openssl-4.0.0~107
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f06bf60fa8bc9e17fc0cdbe97158a1a65db9f2ee;p=thirdparty%2Fopenssl.git

crypto/idea/i_ofb64.c: mask the num value after negativity check

Commit 5ba9029bc7b3 "Mask *num on entry in deprecated low-level OFB/CFB
implementations" introduced masking of the user-supplied num value
in several functions, which rendered the exiting *num negativity check
introduced in 1634b2df9f12 "enc: fix coverity 1451499, 1451501, 1451506,
1451507, 1351511, 1451514, 1451517, 1451523, 1451526m 1451528, 1451539,
1451441, 1451549, 1451568 & 1451572: improper use of negative value"
ineffectual.  While commit b73a5743253d "crypto/idea/i_cfb64.c:
condition 'n < 0' can never be met after doing 'n = n & 0x07'"
has addressed the issue in crypto/idea/i_cfb64.c:IDEA_cfb64_encrypt(),
this commit addresses the same issue
in crypto/idea/i_ofb64.c:IDEA_ofb64_encrypt() in similar fashion,
by postponing the masking after the negativity check.

The issue has initially reported by Coverity, ID 1689815.

Resolves: https://scan5.scan.coverity.com/#/project-view/62622/10222?selectedIssue=1689815
Fixes: 5ba9029bc7b3 "Mask *num on entry in deprecated low-level OFB/CFB implementations"
References: b73a5743253d "crypto/idea/i_cfb64.c: condition 'n < 0' can never be met after doing 'n = n & 0x07'"
Co-Authored-by: Alexandr Nedvedicky <sashan@openssl.org>
Signed-off-by: Eugene Syromiatnikov <esyr@openssl.org>

Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Nikola Pajkovsky <nikolap@openssl.org>
MergeDate: Tue Mar 24 17:52:35 2026
(Merged from https://github.com/openssl/openssl/pull/30528)

(cherry picked from commit fae68066ec117bd0d38166687e9bc62fd43bd42f)
---

diff --git a/crypto/idea/i_ofb64.c b/crypto/idea/i_ofb64.c
index c92c3ed5e85..64f8469abc6 100644
--- a/crypto/idea/i_ofb64.c
+++ b/crypto/idea/i_ofb64.c
@@ -27,7 +27,7 @@ void IDEA_ofb64_encrypt(const unsigned char *in, unsigned char *out,
     unsigned char *ivec, int *num)
 {
     register unsigned long v0, v1, t;
-    register int n = *num & 0x07;
+    register int n = *num;
     register long l = length;
     unsigned char d[8];
     register char *dp;
@@ -39,6 +39,7 @@ void IDEA_ofb64_encrypt(const unsigned char *in, unsigned char *out,
         *num = -1;
         return;
     }
+    n = n & 0x07;
 
     iv = (unsigned char *)ivec;
     n2l(iv, v0);