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|
the snmp_pdu_parse() function could leave
incompletely parsed varBind variables in the list of variables in
case the parsing of the SNMP PDU failed. If later processing tries to
operate on the stale and incompletely processed varBind (e.g. when
printing the variables), this can lead to e.g. crashes or, possibly,
execution of arbitrary code
Upstream-Status: Backport [net-snmp]
Written-by: Robert Story
diff -Nur net-snmp-5.7.2.1.orig/snmplib/snmp_api.c net-snmp-5.7.2.1/snmplib/snmp_api.c
--- net-snmp-5.7.2.1.orig/snmplib/snmp_api.c 2015-05-27 11:25:11.563747471 +0800
+++ net-snmp-5.7.2.1/snmplib/snmp_api.c 2015-05-27 13:27:27.724748201 +0800
@@ -4345,10 +4345,9 @@
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];
/*
@@ -4487,38 +4486,24 @@
(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 (NULL == vptemp) {
- return -1;
- }
- if (NULL == vp) {
- pdu->variables = vptemp;
- } else {
- vp->next_variable = vptemp;
- }
- vp = vptemp;
+ vp = SNMP_MALLOC_TYPEDEF(netsnmp_variable_list);
+ if (NULL == vp)
+ goto fail;
- vp->next_variable = NULL;
- vp->val.string = NULL;
vp->name_length = MAX_OID_LEN;
- vp->name = NULL;
- vp->index = 0;
- vp->data = NULL;
- vp->dataFreeHook = NULL;
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");
@@ -4583,7 +4568,7 @@
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);
@@ -4594,7 +4579,7 @@
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;
@@ -4606,19 +4591,35 @@
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);
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;
}
/*
|
