Don't Overflow when printing Thawte Strong Extranet Version

When printing human readable info on the Thawte Strong Extranet extension
the version number could overflow if the version number == LONG_MAX. This
is undefined behaviour.

Issue found by OSSFuzz.

Reviewed-by: Ben Kaduk <kaduk@mit.edu>
(Merged from https://github.com/openssl/openssl/pull/13452)

diff --git a/crypto/x509/v3_sxnet.c b/crypto/x509/v3_sxnet.c
index 76f5eafc73dd50615f5afc0ec5b32275baddb522..6e2b796a3816869ab795d7f74ff4669aa28ada15 100644 (file)
--- a/crypto/x509/v3_sxnet.c
+++ b/crypto/x509/v3_sxnet.c
@@ -57,12 +57,24 @@ IMPLEMENT_ASN1_FUNCTIONS(SXNET)
 static int sxnet_i2r(X509V3_EXT_METHOD *method, SXNET *sx, BIO *out,
                      int indent)
 {
-    long v;
+    int64_t v;
     char *tmp;
     SXNETID *id;
     int i;
-    v = ASN1_INTEGER_get(sx->version);
-    BIO_printf(out, "%*sVersion: %ld (0x%lX)", indent, "", v + 1, v);
+
+    /*
+     * Since we add 1 to the version number to display it, we don't support
+     * LONG_MAX since that would cause on overflow.
+     */
+    if (!ASN1_INTEGER_get_int64(&v, sx->version)
+            || v >= LONG_MAX
+            || v < LONG_MIN) {
+        BIO_printf(out, "%*sVersion: <unsupported>", indent, "");
+    } else {
+        long vl = (long)v;
+
+        BIO_printf(out, "%*sVersion: %ld (0x%lX)", indent, "", vl + 1, vl);
+    }
     for (i = 0; i < sk_SXNETID_num(sx->ids); i++) {
         id = sk_SXNETID_value(sx->ids, i);
         tmp = i2s_ASN1_INTEGER(NULL, id->zone);

diff --git a/fuzz/corpora/crl/4d72381f46c50eb9cabd8aa27f456962bf013b28 b/fuzz/corpora/crl/4d72381f46c50eb9cabd8aa27f456962bf013b28
new file mode 100644 (file)
index 0000000..dde1c66
Binary files /dev/null and b/fuzz/corpora/crl/4d72381f46c50eb9cabd8aa27f456962bf013b28 differ