This patch fixes a security issue where snmp_pdu_parse() function 

could leave incompletely parsed varBind variables in the list of  

variables. A remote, unauthenticated attacker could exploit this 

flaw to cause a crash or, potentially, execute arbitrary code.

The vulnerability is fixed in the upsream and below is the link 

to the upstream bug.

https://sourceforge.net/p/net-snmp/bugs/2615/ 

--- a/snmplib/snmp_api.c	Mon Aug  3 03:34:05 2015

+++ b/snmplib/snmp_api.c	Mon Aug  3 03:31:01 2015

@@ -4270,10 +4270,9 @@

     u_char          type;

     u_char          msg_type;

     u_char         *var_val;

-    int             badtype = 0;

     size_t          len;

     size_t          four;

-    netsnmp_variable_list *vp = NULL;

+    netsnmp_variable_list *vp = NULL, *vplast = NULL;

     oid             objid[MAX_OID_LEN];

     /*

@@ -4408,38 +4407,23 @@

                               (ASN_SEQUENCE | ASN_CONSTRUCTOR),

                               "varbinds");

     if (data == NULL)

-        return -1;

-

+        goto fail;

     /*

      * get each varBind sequence 

      */

     while ((int) *length > 0) {

-        netsnmp_variable_list *vptemp;

-        vptemp = (netsnmp_variable_list *) malloc(sizeof(*vptemp));

-        if (0 == vptemp) {

-            return -1;

-        }

-        if (0 == vp) {

-            pdu->variables = vptemp;

-        } else {

-            vp->next_variable = vptemp;

-        }

-        vp = vptemp;

-

-        vp->next_variable = NULL;

-        vp->val.string = NULL;

+        vp = SNMP_MALLOC_TYPEDEF(netsnmp_variable_list);

+        if (NULL == vp)

+            goto fail;

         vp->name_length = MAX_OID_LEN;

-        vp->name = 0;

-        vp->index = 0;

-        vp->data = 0;

-        vp->dataFreeHook = 0;

+        vp->type = 0;

         DEBUGDUMPSECTION("recv", "VarBind");

         data = snmp_parse_var_op(data, objid, &vp->name_length, &vp->type,

                                  &vp->val_len, &var_val, length);

         if (data == NULL)

-            return -1;

+            goto fail; 

         if (snmp_set_var_objid(vp, objid, vp->name_length))

-            return -1;

+            goto fail;

         len = MAX_PACKET_LENGTH;

         DEBUGDUMPHEADER("recv", "Value");

@@ -4504,7 +4488,7 @@

                 vp->val.string = (u_char *) malloc(vp->val_len);

             }

             if (vp->val.string == NULL) {

-                return -1;

+                goto fail;

             }

             asn_parse_string(var_val, &len, &vp->type, vp->val.string,

                              &vp->val_len);

@@ -4515,7 +4499,7 @@

             vp->val_len *= sizeof(oid);

             vp->val.objid = (oid *) malloc(vp->val_len);

             if (vp->val.objid == NULL) {

-                return -1;

+                goto fail;

             }

             memmove(vp->val.objid, objid, vp->val_len);

             break;

@@ -4527,7 +4511,7 @@

         case ASN_BIT_STR:

             vp->val.bitstring = (u_char *) malloc(vp->val_len);

             if (vp->val.bitstring == NULL) {

-                return -1;

+                goto fail;

             }

             asn_parse_bitstring(var_val, &len, &vp->type,

                                 vp->val.bitstring, &vp->val_len);

@@ -4534,12 +4518,25 @@

             break;

         default:

             snmp_log(LOG_ERR, "bad type returned (%x)\n", vp->type);

-            badtype = -1;

+            goto fail;

             break;

         }

         DEBUGINDENTADD(-4);

+        if (NULL == vplast) {

+            pdu->variables = vp;

+        } else {

+            vplast->next_variable = vp;

+        }

+        vplast = vp;

+        vp = NULL;

     }

-    return badtype;

+    return 0;

+    fail:

+      DEBUGMSGTL(("recv", "error while parsing VarBindList\n"));

+      /** if we were parsing a var, remove it from the pdu and free it */

+      if (vp)

+        snmp_free_var(vp);

+      return -1;

 }

 /*