From: Bruno Haible <bruno@clisp.org>
Date: Tue, 12 Aug 2025 00:25:41 +0000 (+0200)
Subject: basenc: Don't trigger undefined behaviour in mini-gmp
X-Git-Tag: v9.8~110
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=f4d339c934a4e737e98cb0e29cc266b790ed1f77;p=thirdparty%2Fcoreutils.git

basenc: Don't trigger undefined behaviour in mini-gmp

* src/basenc.c (base58_encode): Avoid calling mpz_import on an empty
limb sequence.
---

diff --git a/src/basenc.c b/src/basenc.c
index dbe3b388f3..84789e2de9 100644
--- a/src/basenc.c
+++ b/src/basenc.c
@@ -1175,10 +1175,12 @@ base58_encode (char const* data, size_t data_len,
   /* Use GMP to convert from base 256 to base 58.  */
   mpz_t num;
   mpz_init (num);
-  mpz_import (num, data_len - zeros, 1, 1, 0, 0, data + zeros);
   if (data_len - zeros)
-    for (p = mpz_get_str (p, 58, num); *p; p++)
-      *p = gmp_to_base58[to_uchar (*p)];
+    {
+      mpz_import (num, data_len - zeros, 1, 1, 0, 0, data + zeros);
+      for (p = mpz_get_str (p, 58, num); *p; p++)
+        *p = gmp_to_base58[to_uchar (*p)];
+    }
   mpz_clear (num);
 
   *outlen = p - out;