Fix various integer issues

In kdc_util.c and spnego_mech.c, error returns from ASN.1 length
functions could be ignored because they were assigned to unsigned
values.  In spnego_mech.c, two buffer size checks could be rewritten
to reduce the likelihood of pointer overflow.  In dump.c and
kdc_preauth.c, calloc() could be used to simplify the code and avoid
multiplication overflow.  In pkinit_clnt.c, the wrong value was
checked for a null result from malloc(), and the code could be
simplified.

Reported by Nickolai Zeldovich <nickolai@csail.mit.edu>.

ticket: 7488

5 files changed, 19 insertions, 39 deletions

diff --git a/src/kadmin/dbutil/dump.c b/src/kadmin/dbutil/dump.c
index cbd2d477a..7b515bd70 100644
--- a/src/kadmin/dbutil/dump.c
+++ b/src/kadmin/dbutil/dump.c
@@ -2109,7 +2109,7 @@ process_k5beta6_record(char *fname, krb5_context kcontext, FILE *filep,
     dbentry->n_tl_data = t3;
 
     /* Get memory for key list */
-    if (t4 && (kp = malloc(t4*sizeof(krb5_key_data))) == NULL)
+    if (t4 && (kp = calloc(t4, sizeof(krb5_key_data))) == NULL)
         goto cleanup;
 
     /* Get memory for extra data */
@@ -2121,7 +2121,6 @@ process_k5beta6_record(char *fname, krb5_context kcontext, FILE *filep,
     dbentry->e_length = t5;
 
     if (kp != NULL) {
-        memset(kp, 0, t4*sizeof(krb5_key_data));
         dbentry->key_data = kp;
         kp = NULL;
     }
diff --git a/src/kdc/kdc_preauth.c b/src/kdc/kdc_preauth.c
index 29485a34d..42a37a848 100644
--- a/src/kdc/kdc_preauth.c
+++ b/src/kdc/kdc_preauth.c
@@ -470,11 +470,10 @@ client_keys(krb5_context context, krb5_kdcpreauth_rock rock,
     krb5_key_data *entry_key;
     int i, k;
 
-    keys = malloc(sizeof(krb5_keyblock) * (request->nktypes + 1));
+    keys = calloc(request->nktypes + 1, sizeof(krb5_keyblock));
     if (keys == NULL)
         return ENOMEM;
 
-    memset(keys, 0, sizeof(krb5_keyblock) * (request->nktypes + 1));
     k = 0;
     for (i = 0; i < request->nktypes; i++) {
         entry_key = NULL;
diff --git a/src/kdc/kdc_util.c b/src/kdc/kdc_util.c
index ea11f54d1..a6a53a1c9 100644
--- a/src/kdc/kdc_util.c
+++ b/src/kdc/kdc_util.c
@@ -842,9 +842,10 @@ fetch_asn1_field(unsigned char *astream, unsigned int level,
                     /* return length and data */
                     astream++;
                     savelen = *astream;
-                    if ((data->length = asn1length(&astream)) < 0) {
+                    if ((length = asn1length(&astream)) < 0) {
                         return(-1);
                     }
+                    data->length = length;
                     /* if the field length is indefinite, we will have to subtract two
                        (terminating octets) from the length returned since we don't want
                        to pass any info from the "wrapper" back.  asn1length will always return
diff --git a/src/lib/gssapi/spnego/spnego_mech.c b/src/lib/gssapi/spnego/spnego_mech.c
index 812c16df6..696f42df5 100644
--- a/src/lib/gssapi/spnego/spnego_mech.c
+++ b/src/lib/gssapi/spnego/spnego_mech.c
@@ -3998,7 +3998,7 @@ g_verify_neg_token_init(unsigned char **buf_in, unsigned int cur_size)
 {
 	unsigned char *buf = *buf_in;
 	unsigned char *endptr = buf + cur_size;
-	unsigned int seqsize;
+	int seqsize;
 	int ret = 0;
 	unsigned int bytes;
 
@@ -4022,7 +4022,7 @@ g_verify_neg_token_init(unsigned char **buf_in, unsigned int cur_size)
 		/*
 		 * Make sure we have the entire buffer as described
 		 */
-		if (buf + seqsize > endptr)
+		if (seqsize > endptr - buf)
 			return (G_BAD_TOK_HEADER);
 	} else {
 		return (G_BAD_TOK_HEADER);
@@ -4039,7 +4039,7 @@ g_verify_neg_token_init(unsigned char **buf_in, unsigned int cur_size)
 		/*
 		 * Make sure we have the entire buffer as described
 		 */
-		if (buf + bytes > endptr)
+		if (seqsize > endptr - buf)
 			return (G_BAD_TOK_HEADER);
 	} else {
 		return (G_BAD_TOK_HEADER);
diff --git a/src/plugins/preauth/pkinit/pkinit_clnt.c b/src/plugins/preauth/pkinit/pkinit_clnt.c
index 7a069c1ed..75b97c6a8 100644
--- a/src/plugins/preauth/pkinit/pkinit_clnt.c
+++ b/src/plugins/preauth/pkinit/pkinit_clnt.c
@@ -1406,40 +1406,21 @@ pkinit_client_plugin_fini(krb5_context context, krb5_clpreauth_moddata moddata)
 static krb5_error_code
 add_string_to_array(krb5_context context, char ***array, const char *addition)
 {
-    char **out = NULL;
-
-    if (*array == NULL) {
-        out = malloc(2 * sizeof(char *));
-        if (out == NULL)
-            return ENOMEM;
-        out[1] = NULL;
-        out[0] = strdup(addition);
-        if (out[0] == NULL) {
-            free(out);
-            return ENOMEM;
-        }
-    } else {
-        int i;
-        char **a = *array;
-        for (i = 0; a[i] != NULL; i++);
-        out = malloc( (i + 2) * sizeof(char *));
-        if (out == NULL)
-            return ENOMEM;
-        for (i = 0; a[i] != NULL; i++) {
-            out[i] = a[i];
-        }
-        out[i++] = strdup(addition);
-        if (out == NULL) {
-            free(out);
-            return ENOMEM;
-        }
-        out[i] = NULL;
-        free(*array);
-    }
-    *array = out;
+    char **a = *array;
+    size_t len;
 
+    for (len = 0; a != NULL && a[len] != NULL; len++);
+    a = realloc(a, (len + 2) * sizeof(char *));
+    if (a == NULL)
+        return ENOMEM;
+    *array = a;
+    a[len] = strdup(addition);
+    if (a[len] == NULL)
+        return ENOMEM;
+    a[len + 1] = NULL;
     return 0;
 }
+
 static krb5_error_code
 handle_gic_opt(krb5_context context,
                pkinit_context plgctx,